National Instruments Time Clock NI 4882 User Manual

™

NI-488.2

User Manual for Windows

January 1996 Edition

Part Number 370902A-01

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Limited Warranty

The media on which you receive National Instruments software are warranted not to fail

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period of 90 days from date of shipment, as evidenced by receipts or other

documentation. National Instruments will, at its option, repair or replace software media

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National Instruments believes that the information in this manual is accurate. The

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™

NI-488 , NI-488.2 , and TNT4882C are trademarks of National Instruments

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Product and company names listed are trademarks or trade names of their respective

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WARNING REGARDING MEDICAL AND CLINICAL

USE OF NATIONAL INSTRUMENTS PRODUCTS

National Instruments products are not designed with components and testing intended to

ensure a level of reliability suitable for use in treatment and diagnosis of humans.

Applications of National Instruments products involving medical or clinical treatment can

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of the user or application designer. Any use or application of National Instruments

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Contents

About This Manual ............................................................................................... xiii

How to Use This Manual Set........................................................................... xiii

Organization of This Manual........................................................................... xiv

Conventions Used in This Manual................................................................... xv

Related Documentation ................................................................................... xvi

Customer Communication ............................................................................... xvi

Chapter One

Introduction.............................................................................................................. 1-1

GPIB Overview ............................................................................................... 1-1

Talkers, Listeners, and Controllers ................................................... 1-1

Controller-In-Charge and System Controller .................................... 1-1

GPIB Addressing............................................................................... 1-2

Sending Messages Across the GPIB ................................................. 1-2

Data Lines ........................................................................... 1-2

Handshake Lines................................................................. 1-3

Interface Management Lines............................................... 1-3

Setting Up and Configuring Your System......................................... 1-4

Controlling More Than One Board..................................... 1-5

Configuration Requirements ............................................................. 1-5

The NI-488.2 Software Package ...................................................................... 1-6

NI-488.2 Driver and Driver Utilities................................................. 1-6

C Language Files............................................................................... 1-7

Visual Basic Language Files ............................................................. 1-7

Win 32s Files..................................................................................... 1-8

Sample Application Files .................................................................. 1-8

How the NI-488.2 Software Works with Windows......................................... 1-8

Unloading and Reloading the NI-488.2 Driver ............................................... 1-9

Chapter 2

Application Examples........................................................................................... 2-1

Example 1: Basic Communication ................................................................. 2-2

Example 2: Clearing and Triggering Devices................................................. 2-4

Example 3: Asynchronous I/O........................................................................ 2-6

Example 4: End-of-String Mode..................................................................... 2-8

Example 5: Service Requests.......................................................................... 2-10

Example 6: Basic Communication with IEEE 488.2-Compliant Devices ..... 2-14

Example 7: Serial Polls Using NI-488.2 Routines ......................................... 2-16

Example 8: Parallel Polls ................................................................................ 2-18

Example 9: Non-Controller Example ............................................................. 2-20

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Contents

Chapter 3

Developing Your Application ............................................................................ 3-1

Choosing How to Access the NI-488.2 DLL................................................... 3-1

Choosing Between NI-488 Functions and NI-488.2 Routines ........................ 3-1

Using NI-488 Functions: One Device for Each Board..................... 3-2

NI-488 Device Functions .................................................... 3-2

NI-488 Board Functions ..................................................... 3-2

Using NI-488.2 Routines: Multiple Boards and/or Multiple

Devices .............................................................................................. 3-3

Checking Status with Global Variables........................................................... 3-3

Status Word – ibsta ........................................................................... 3-3

Error Variable – iberr ........................................................................ 3-5

Count Variables – ibcnt and ibcntl .................................................... 3-5

Using wibic to Communicate with Devices..................................................... 3-5

Writing Your NI-488 Application ................................................................... 3-6

Items to Include ................................................................................. 3-6

NI-488 Program Shell ....................................................................... 3-7

General Program Steps and Examples .............................................. 3-8

Step 1. Open a Device........................................................ 3-8

Step 2. Clear the Device..................................................... 3-8

Step 3. Configure the Device ............................................. 3-9

Step 4. Trigger the Device ................................................. 3-9

Step 5. Wait for the Measurement ..................................... 3-9

Step 6. Read the Measurement........................................... 3-10

Step 7. Process the Data..................................................... 3-10

Step 8. Place the Device Offline ........................................ 3-10

Writing Your NI-488.2 Application ................................................................ 3-11

Items to Include ................................................................................. 3-11

NI-488.2 Program Shell..................................................................... 3-12

General Program Steps and Examples .............................................. 3-13

Step 1. Initialization ........................................................... 3-13

Step 2. Find All Listeners .................................................. 3-13

Step 3. Identify the Instrument........................................... 3-13

Step 4. Initialize the Instrument ......................................... 3-14

Step 5. Configure the Instrument ....................................... 3-15

Step 6. Trigger the Instrument ........................................... 3-15

Step 7. Wait for the Measurement ..................................... 3-15

Step 8. Read the Measurement........................................... 3-16

Step 9. Process the Data..................................................... 3-16

Step 10. Place the Board Offline........................................ 3-16

Compiling, Linking, and Running Your Application ...................................... 3-17

Microsoft C ....................................................................................... 3-17

Borland C++ ...................................................................................... 3-17

Visual Basic....................................................................................... 3-18

Direct Entry with C ........................................................................... 3-18

Method 1. List Functions in the

Module Definition File..................................... 3-19

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Contents

Method 2. Generate an Import Library

Using implib..................................................... 3-20

Method 3. Use LoadLibrary and GetProcAddress............. 3-20

Direct Entry with Visual Basic.......................................................... 3-23

Chapter 4

Debugging Your Application............................................................................. 4-1

Running wibtest ............................................................................................... 4-1

Presence Test of Driver ..................................................................... 4-1

Presence Test of Board...................................................................... 4-1

GPIB Cables Connected .................................................................... 4-2

Running GPIBInfo........................................................................................... 4-2

Debugging with the Global Status Variables................................................... 4-3

Debugging with wibic...................................................................................... 4-4

Debugging with GPIB Spy .............................................................................. 4-4

GPIB Error Codes ............................................................................................ 4-4

Configuration Errors ........................................................................................ 4-5

Timing Errors................................................................................................... 4-6

Communication Errors..................................................................................... 4-6

Repeat Addressing............................................................................. 4-6

Termination Method.......................................................................... 4-6

Common Questions ......................................................................................... 4-7

Chapter 5

wibic–Windows Interface Bus Interactive Control Utility ................... 5-1

Overview.......................................................................................................... 5-1

Example Using NI-488 Functions ................................................................... 5-1

wibic Syntax..................................................................................................... 5-4

Number Syntax.................................................................................. 5-4

String Syntax ..................................................................................... 5-5

Address Syntax.................................................................................. 5-5

wibic Syntax for NI-488 Functions ................................................... 5-5

wibic Syntax for NI-488.2 Routines ................................................. 5-8

Status Word ..................................................................................................... 5-9

Error Information............................................................................................. 5-9

Count................................................................................................................ 5-10

Common NI-488 Functions ............................................................................. 5-10

ibfind ................................................................................................. 5-10

ibdev .................................................................................................. 5-10

ibwrt................................................................................................... 5-12

ibrd..................................................................................................... 5-12

Common NI-488.2 Routines in wibic.............................................................. 5-13

Set ...................................................................................................... 5-13

Send and SendList ............................................................................. 5-13

Receive .............................................................................................. 5-13

Auxiliary Functions ......................................................................................... 5-14

Set (Select Device or Board) ............................................................. 5-15

Help (Display Help Information) ...................................................... 5-15

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Contents

! (Repeat Previous Function)............................................................. 5-15

- (Turn OFF Display) and + (Turn ON Display)............................... 5-15

n* (Repeat Function n Times) ........................................................... 5-16

$ (Execute Indirect File).................................................................... 5-16

Print (Display the ASCII String) ....................................................... 5-17

Buffer (Set Buffer Display Mode)..................................................... 5-17

Chapter 6

GPIB Spy ................................................................................................................... 6-1

Overview.......................................................................................................... 6-1

Starting GPIB Spy ........................................................................................... 6-1

Exiting GPIB Spy ............................................................................................ 6-2

Viewing Call Details........................................................................................ 6-2

GPIB Spy Configuration Options .................................................................... 6-3

Calls to Highlight .............................................................................. 6-3

Calls To Trap On............................................................................... 6-3

Buffer History ................................................................................... 6-3

Set Highlight Color ........................................................................... 6-3

Store Configuration ........................................................................... 6-4

GPIB Spy Output Options ............................................................................... 6-4

To Screen........................................................................................... 6-4

To File ............................................................................................... 6-4

Clear Screen....................................................................................... 6-4

GPIB Spy Help ................................................................................................ 6-5

Performance Considerations ............................................................................ 6-5

Chapter 7

GPIB Programming Techniques ..................................................................... 7-1

Termination of Data Transfers......................................................................... 7-1

High-Speed Data Transfers (HS488)............................................................... 7-2

Enabling HS488................................................................................. 7-2

System Configuration Effects on HS488 .......................................... 7-3

Waiting for GPIB Conditions .......................................................................... 7-3

Device-Level Calls and Bus Management....................................................... 7-3

Talker/Listener Applications ........................................................................... 7-4

Waiting for Messages from the Controller ........................................ 7-4

Using the Event Queue...................................................................... 7-5

Requesting Service ............................................................................ 7-5

Serial Polling ................................................................................................... 7-5

Service Requests from IEEE 488 Devices ........................................ 7-5

Service Requests from IEEE 488.2 Devices ..................................... 7-6

Automatic Serial Polling ................................................................... 7-6

Stuck SRQ State.................................................................. 7-6

Autopolling and Interrupts .................................................. 7-7

SRQ and Serial Polling with NI-488 Device Functions.................... 7-7

SRQ and Serial Polling with NI-488.2 Routines............................... 7-8

Example 1: Using FindRQS............................................... 7-9

Example 2: Using AllSpoll ................................................ 7-9

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viii

Contents

Parallel Polling................................................................................................. 7-10

Implementing a Parallel Poll ............................................................. 7-10

Parallel Polling with NI-488 Functions .............................. 7-10

Parallel Polling with NI-488.2 Routines............................. 7-12

Chapter 8

wibconf–Windows Interface Bus Configuration Utility......................... 8-1

Overview.......................................................................................................... 8-1

Starting wibconf............................................................................................... 8-1

Upper and Lower Levels of wibconf ............................................................... 8-2

Upper Level Device Map .................................................................. 8-3

Device Maps of the Boards................................................. 8-4

Help..................................................................................... 8-4

Rename ............................................................................... 8-4

(Dis)connect ........................................................................ 8-4

Edit ...................................................................................... 8-5

Exit ...................................................................................... 8-5

Lower Level Device/Board Characteristics....................................... 8-5

Change Characteristics........................................................ 8-6

Change Board or Device..................................................... 8-6

Help..................................................................................... 8-6

Reset Value ......................................................................... 8-6

Return to Map ..................................................................... 8-6

Board and Device Configuration Options ....................................................... 8-7

Primary GPIB Address ...................................................................... 8-7

Secondary GPIB Address .................................................................. 8-7

Timeout Setting ................................................................................. 8-7

Serial Poll Timeouts (Device Characteristic Only)........................... 8-8

Terminate Read on EOS.................................................................... 8-8

Set EOI with EOS on Writes............................................................. 8-8

Type of Compare on EOS ................................................................. 8-8

EOS Byte........................................................................................... 8-8

Send EOI at End of Write ................................................................. 8-9

System Controller (Board Characteristic Only) ................................ 8-9

Assert REN when SC (Board Characteristic Only)........................... 8-9

Enable Auto Serial Polling (Board Characteristic Only) .................. 8-9

Enable CIC Protocol (Board Characteristic Only) ............................ 8-9

Bus Timing (Board Characteristic Only) .......................................... 8-10

Cable Length for High Speed (Board Characteristic Only) .............. 8-10

Parallel Poll Duration (Board Characteristic Only)........................... 8-10

Use This GPIB Interface (Board Characteristic Only)...................... 8-10

Base I/O Address (Board Description Only)..................................... 8-10

DMA Channel (Board Characteristic Only)...................................... 8-11

Interrupt Jumper Setting (Board Characteristic Only) ...................... 8-11

Serial Poll Timeout (Device Characteristic Only)............................. 8-11

Enable Repeat Addressing (Device Characteristic Only) ................. 8-11

GPIB-PCII/IIA Mode Switch ............................................................ 8-11

Default Configurations in wibconf .................................................................. 8-12

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Contents

Exiting wibconf ............................................................................................... 8-12

Checking for Errors ........................................................................... 8-13

wibconf Batch Mode........................................................................................ 8-13

Appendix A

Status Word Conditions ...................................................................................... A-1

Appendix B

Error Codes and Solutions ................................................................................. B-1

Appendix C

Customer Communication ................................................................................. C-1

Glossary......................................................................................................... Glossary-1

Index ..................................................................................................................... Index-1

Figures

Figure 1-1. GPIB Address Bits ..................................................................................... 1-2

Figure 1-2. Linear and Star System Configuration ....................................................... 1-4

Figure 1-3. Example of Multiboard System Setup ....................................................... 1-5

Figure 1-4. How the NI-488.2 Software Works with Windows ................................... 1-8

Figure 2-1. Program Flowchart for Example 1 ............................................................. 2-3

Figure 2-2. Program Flowchart for Example 2 ............................................................. 2-5

Figure 2-3. Program Flowchart for Example 3 ............................................................. 2-7

Figure 2-4. Program Flowchart for Example 4 ............................................................. 2-9

Figure 2-5. Program Flowchart for Example 5 ............................................................. 2-12

Figure 2-6. Program Flowchart for Example 6 ............................................................. 2-15

Figure 2-7. Program Flowchart for Example 7 ............................................................. 2-17

Figure 2-8. Program Flowchart for Example 8 ............................................................. 2-19

Figure 2-9. Program Flowchart for Example 9 ............................................................. 2-21

Figure 3-1. General Program Shell Using NI-488 Device Functions ........................... 3-7

Figure 3-2. General Program Shell Using NI-488.2 Routines ...................................... 3-12

Figure 6-1. Main GPIB Spy Window ........................................................................... 6-1

Figure 6-2 GPIB Spy Call Details Window for ibwrt................................................... 6-2

Figure 8-1. Upper Level of wibconf ............................................................................. 8-3

Figure 8-2. Lower Level of wibconf ............................................................................. 8-5

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Contents

Tables

Table 1-1. GPIB Handshake Lines ............................................................................... 1-3

Table 1-2. GPIB Interface Management Lines ............................................................. 1-3

Table 3-1. Status Word (ibsta) Layout .......................................................................... 3-4

Table 4-1. GPIB Error Codes ........................................................................................ 4-5

Table 5-1. Syntax for Device-Level NI-488 Functions in wibic................................... 5-6

Table 5-2. Syntax for Board-Level NI-488 Functions in wibic .................................... 5-7

Table 5-3. Syntax for NI-488.2 Routines in wibic ........................................................ 5-8

Table 5-4. Auxiliary Functions in wibic ....................................................................... 5-14

Table 8-1. Options for Starting wibconf ....................................................................... 8-2

Table 8-2. wibconf Batch Mode Command Pairs......................................................... 8-15

Table A-1. Status Word Bits ......................................................................................... A-1

Table B-1. GPIB Error Codes ....................................................................................... B-1

NI-488.2 User Manual for Windows

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About This Manual

This manual describes the features and functions of the NI-488.2 software for Windows.

The NI-488.2 software is meant to be used with Microsoft Windows version 3.0 or

higher. This manual assumes that you are already familiar with Windows.

How to Use This Manual Set

Getting Started

Manual

Installation and

Configuration

Experienced

Users

Novice

Users

NI-488.2 Function

Reference Manual

for DOS/Windows

NI-488.2 User

Manual for Windows

Function

and Routine

Descriptions

Application

Development

and Examples

Use the getting started manual to install and configure your GPIB hardware and NI-488.2

software for Windows.

Use the NI-488.2 User Manual for Windows to learn the basics of GPIB and how to

develop an application program. The user manual also contains debugging information

and detailed examples.

Use the NI-488.2 Function Reference Manual for DOS/Windows for specific information

about each NI-488 function and NI-488.2 routine such as format, parameters, and

possible errors.

xiii

NI-488.2 User Manual for Windows

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About This Manual

Organization of This Manual

This manual is organized as follows:

• Chapter 1, Introduction, gives an overview of GPIB and the NI-488.2 software.

• Chapter 2, Application Examples, contains nine sample applications designed to

illustrate specific GPIB concepts and techniques that can help you write your own

applications. The description of each example includes the programmer's task, a

program flowchart, and numbered steps which correspond to the numbered blocks on

the flowchart.

• Chapter 3, Developing Your Application, explains how to develop a GPIB application

program using NI-488 functions and NI-488.2 routines.

• Chapter 4, Debugging Your Application, describes several ways to debug your

application program.

• Chapter 5, wibic–Windows Interface Bus Interactive Control, introduces you to

wibic, the interactive control program that you can use to communicate with GPIB

devices interactively.

• Chapter 6, GPIB Spy, explains how to use the GPIB Spy utility to monitor and debug

your application program.

• Chapter 7, GPIB Programming Techniques, describes techniques for using some

NI-488 functions and NI-488.2 routines in your application program.

• Chapter 8, wibconf–Windows Interface Bus Configuration Utility, contains a

description of wibconf, the software configuration program you can use to configure

the NI-488.2 software for Windows.

• Appendix A, Status Word Conditions, gives a detailed description of the conditions

reported in the status word, ibsta.

• Appendix B, Error Codes and Solutions, lists a description of each error, some

conditions under which it might occur, and possible solutions.

• Appendix C, Customer Communication, contains forms you can use to request help

from National Instruments or to comment on our products and manuals.

• The Glossary contains an alphabetical list and description of terms used in this manual,

including abbreviations, acronyms, metric prefixes, mnemonics, and symbols.

• The Index contains an alphabetical list of key terms and topics in this manual,

including the page where you can find each one.

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xiv

About This Manual

Conventions Used in This Manual

The following conventions are used in this manual.

bold

Text in bold denotes windows, menus, menu options, and

dialog box options.

bold italic

Bold italic text denotes a note, caution, or warning.

italic

Italic text denotes emphasis, cross references, field names, or

an introduction to a key concept.

monospace

Text in this font denotes text or characters that you enter from

the keyboard. Sections of code, programming examples, and

syntax examples also appear in this font. This font is also

used for the proper name of disk drives, paths, directories,

device names, variables, and for statements taken from

program code.

bold monospace

Bold text in this font denotes the messages and responses that

the computer automatically prints to the screen.

italic monospace Italic text in this font denotes that you must supply the

appropriate words or values in the place of these items.

< >

Angle brackets enclose the name of a key on the keyboard–for

example, <PageDown>.

A hyphen between two or more key names enclosed in angle

brackets denotes that you should simultaneously press the

named keys–for example, <Control-C>.

IEEE 488 and

IEEE 488.2

IEEE 488 and IEEE 488.2 are used throughout

this manual to refer to the ANSI/IEEE Standard

488.1-1987 and the ANSI/IEEE Standard

488.2-1992, respectively, which define the GPIB.

NI-488.2 software

The term NI-488.2 software is used throughout this manual to

refer to the NI-488.2 software for Windows, unless otherwise

noted.

Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in

the Glossary.

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NI-488.2 User Manual for Windows

About This Manual

Related Documentation

The following documents contain information that you may find helpful as you read this

manual:

• ANSI/IEEE Standard 488.1-1987, IEEE Standard Digital Interface for Programmable

Instrumentation

• ANSI/IEEE Standard 488.2-1992, IEEE Standard Codes, Formats, Protocols, and

Common Commands

• Microsoft Windows User’s Guide

Customer Communication

National Instruments wants to receive your comments on our products and manuals. We

are interested in the applications you develop with our products, and we want to help if

you have problems with them. To make it easy for you to contact us, this manual

contains comment and configuration forms for you to complete. These forms are in

Appendix C, Customer Communication, at the end of this manual.

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xvi

Chapter 1

Introduction

This chapter gives an overview of GPIB and the NI-488.2 software.

GPIB Overview

The ANSI/IEEE Standard 488.1-1987, also known as GPIB (General Purpose Interface

Bus), describes a standard interface for communication between instruments and

controllers from various vendors. It contains information about electrical, mechanical,

and functional specifications. The GPIB is a digital, 8-bit parallel communications

interface with data transfer rates of 1 Mbytes/s and above. The bus supports one System

Controller, usually a computer, and up to 14 additional instruments. The ANSI/IEEE

Standard 488.2-1987 extends IEEE 488.1 by defining a bus communication protocol, a

common set of data codes and formats, and a generic set of common device commands.

Talkers, Listeners, and Controllers

GPIB devices can be Talkers, Listeners, or Controllers. A Talker sends out data

messages. Listeners receive data messages. The Controller, usually a computer,

manages the flow of information on the bus. It defines the communication links and

sends GPIB commands to devices.

Some devices are capable of playing more than one role. A digital voltmeter, for

example, can be a Talker and a Listener. If your personal computer has a National

Instruments GPIB interface board and NI-488.2 software installed, it can function as a

Talker, Listener, and Controller.

Controller-In-Charge and System Controller

You can have multiple Controllers on the GPIB, but only one Controller at a time can be

the active Controller, or Controller-In-Charge (CIC). The CIC can either be active or

inactive (Standby) Controller. Control can pass from the current CIC to an idle

Controller, but only the System Controller, usually a GPIB interface board, can make

itself the CIC.

1-1

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Introduction

Chapter 1

GPIB Addressing

All GPIB devices and boards must be assigned a unique GPIB address. A GPIB address

is made up of two parts: a primary address and an optional secondary address.

The primary address is a number in the range 0 to 30. The GPIB Controller uses this

address to form a talk or listen address that is sent over the GPIB when communicating

with a device.

A talk address is formed by setting bit 6, the TA (Talk Active) bit of the GPIB address.

A listen address is formed by setting bit 5, the LA (Listen Active) bit of the GPIB

address. For example, if a device is at address 1, the Controller sends hex 41 (address 1

with bit 6 set) to make the device a Talker. Because the Controller is usually at primary

address 0, it sends hex 20 (address 0 with bit 5 set) to make itself a Listener. Figure 1-1

shows the configuration of the GPIB address bits.

Bit

Position

Meaning

GPIB Primary Address (range 0 to 30)

Figure 1-1. GPIB Address Bits

With some devices, you can use secondary addressing. A secondary address is a number

in the range hex 60 to hex 7E. When secondary addressing is in use, the Controller sends

the primary talk or listen address of the device followed by the secondary address of the

device.

Sending Messages Across the GPIB

Devices on the bus communicate by sending messages. Signals and lines transfer these

messages across the GPIB interface, which consists of 16 signal lines and eight ground

return (shield drain) lines. The 16 signal lines are discussed in the following sections.

Data Lines

Eight data lines, DIO1 through DIO8, carry both data and command messages.

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1-2

Chapter 1

Introduction

Handshake Lines

Three hardware handshake lines asynchronously control the transfer of message bytes

between devices. This process is a three-wire interlocked handshake, and it guarantees

that devices send and receive message bytes on the data lines without transmission error.

Table 1-1 summarizes the GPIB handshake lines.

Table 1-1. GPIB Handshake Lines

Line

Description

NRFD (not ready for data)

Listening device is ready/not ready to receive a message

byte. Also used by the Talker to signal high-speed GPIB

transfers.

NDAC (not data accepted)

DAV (data valid)

Listening device has/has not accepted a message byte.

Talking device indicates signals on data lines are stable

(valid) data.

Interface Management Lines

Five GPIB hardware lines manage the flow of information across the bus. Table 1-2

summarizes the GPIB interface management lines.

Table 1-2. GPIB Interface Management Lines

Line

Description

ATN (attention)

Controller drives ATN true when it sends commands and

false when it sends data messages.

IFC (interface clear)

REN (remote enable)

SRQ (service request)

EOI (end or identify)

System Controller drives the IFC line to initialize the bus

and make itself CIC.

System Controller drives the REN line to place devices

in remote or local program mode.

Any device can drive the SRQ line to asynchronously

request service from the Controller.

Talker uses the EOI line to mark the end of a data

message. Controller uses the EOI line when it conducts

a parallel poll.

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Introduction

Chapter 1

Setting Up and Configuring Your System

Devices are usually connected with a cable assembly consisting of a shielded

24-conductor cable with both a plug and receptacle connector at each end. With this

design, you can link devices in a linear configuration, a star configuration, or a

combination of the two. Figure 1-2 shows the linear and star configurations.

Linear

Configuration

Device A

Device B

Device C

Star

Configuration

Device D

Device A

Device B

Device C

Figure 1-2. Linear and Star System Configuration

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1-4

Chapter 1

Introduction

Controlling More Than One Board

Multiboard drivers, such as the NI-488.2 driver for Windows, can control more than one

interface board. Figure 1-3 shows an example of a multiboard system configuration.

gpib0 is the access board for the voltmeter, and gpib1 is the access board for the

plotter and printer. The control functions of the devices automatically access their

respective boards.

One

GPIB

Digital Voltmeter

gpib0

Plotter

Another

gpib1

GPIB

Printer

Figure 1-3. Example of Multiboard System Setup

Configuration Requirements

To achieve the high data transfer rate that the GPIB was designed for, you must limit the

physical distance between devices and the number of devices on the bus. The following

restrictions are typical:

•

A maximum separation of four meters between any two devices and an average

separation of two meters over the entire bus.

•

A maximum total cable length of 20 m.

A maximum of 15 devices connected to each bus, with at least two-thirds powered on.

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Introduction

Chapter 1

For high-speed operation, the following restrictions apply:

•

All devices in the system must be powered on.

Cable lengths as short as possible up to a maximum of 15 m of cable for each system.

At least one equivalent device load per meter of cable.

If you want to exceed these limitations, you can use bus extenders to increase the cable

length or expander to increase the number of device loads. Extenders and expanders are

available from National Instruments.

The following sections describe the NI-488.2 software, which controls the flow of

communication on the GPIB.

The NI-488.2 Software Package

The following section highlights important elements of the NI-488.2 software for

Windows and describes the function of each element.

NI-488.2 Driver and Driver Utilities

The NI-488.2 software contains the following driver and utility files:

• readme.txtis a documentation file that contains important information about the

NI-488.2 software and a description of any new features. Before you use the

software, read this file for the most recent information.

• setup.exeis a Windows setup executable that installs the NI-488.2 software.

• gpib.dll is a 16-bit dynamic link library that implements the NI-488 and

NI-488.2 functions.

• gpib.ini is the GPIB configuration information file that describes the default

configuration of the NI-488.2 software.

• nivgpibd.386, the National Instruments virtual GPIB device, allows you to use

DMA to transfer buffers located above 16 MB in memory. The setup program offers

to install this virtual device for you.

• nivdmad.386is an improved version of the virtual DMA device (vdmad) used by

Windows 3.0 in 386-enhanced mode. The setup program offers to install this virtual

device for you if you are running Windows 3.0.

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1-6

Chapter 1

Introduction

• ibdiag.exeis a program that you can use to test the GPIB hardware and ensure

that it is functioning properly.

• wibtest.exeis the Windows NI-488.2 software installation test.

• gpibinfo.exe is a utility you can use to obtain information about your GPIB

hardware and software, such as the version of the NI-488.2 software and the type of

interface board you are using.

• wibic.exeis an interactive control program that you use to communicate with the

GPIB devices interactively using NI-488.2 functions and routines. It helps you to

learn the NI-488.2 routines and to program your instrument or other GPIB devices.

• wibconf.exeis a software configuration program that changes the configuration

parameters of the NI-488.2 software for Windows.

• gpibspy.exeis the GPIB activity monitor program. It is a debugging tool that you

can use to monitor the NI-488.2 calls made by your Windows applications.

C Language Files

The NI-488.2 software contains the following C language files:

• readme.mcis a documentation file that contains information about the C language

interface.

• gpib.lib is the Microsoft C (version 5.1 or higher) and Borland C++ (version 2.0

or higher) language interface library. You must link this library with your application

program so that your program can access the NI-488.2 dynamic link library.

• windecl.his an include file. It contains NI-488 function and NI-488.2 routine

prototypes and various predefined constants.

Visual Basic Language Files

The distribution disk contains the following language files for Microsoft Visual Basic:

• readme.vbis a documentation file that contains information about the Visual Basic

language interface.

• vbib.bas is the Visual Basic (version 1.0 or higher) language source file which

defines the NI-488 functions and NI-488.2 routines that call the gpib.dll.

• niglobal.basis the Visual Basic global module that includes certain predefined

constant declarations and declares the global variables.

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Introduction

Chapter 1

Win 32s Files

• gpib-32.dllis a 32-bit translation dynamic link library that handles the 32-bit to

16-bit translation.

• gpib-16.dllis a 16-bit translation dynamic link library.

• wibic32.exeis a Win32s version of the wibic application.

Sample Application Files

The NI-488.2 software includes nine sample applications along with source code for each

language supported by the NI-488.2 software. For a detailed description of the sample

application files, refer to Chapter 2, Application Examples.

How the NI-488.2 Software Works with Windows

The NI-488.2 driver is a standard 16-bit Windows DLL, which is loaded when a

Windows GPIB application is executed. The NI-488.2 driver for Windows is unloaded

when the last active GPIB application is exited.

Figure 1-4 shows how the NI-488.2 software works with Windows and your GPIB

hardware.

WIBIC

32-bit Utility

for Using

NI-488.2

Commands

Interactively

WIBIC

16-bit Utility

for Using

NI-488.2

Commands

Interactively

Win 32s

User

Application

Program

Win16

User

Application

Program

Win 32s User

Application

Program that

Uses Direct

Entry

Win16 User

Application

Program that

Uses Direct

Entry

32-bit NI-488.2 Language Interface

16-bit NI-488.2 Language Interface

Windows

32-bit NI-488.2

Translation DLL

16-bit NI-488.2

Translation DLL

16-bit NI-488.2 DLL

GPIB Hardware Interface

Figure 1-4. How the NI-488.2 Software Works with Windows

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Chapter 1

Introduction

Unloading and Reloading the NI-488.2 Driver

The NI-488.2 driver for Windows is a dynamic link library (DLL), which is loaded and

unloaded automatically. When a Windows application first accesses the NI–488.2 DLL,

it loads the DLL into memory. When the last Windows application using the NI-488.2

DLL has exited, the DLL is unloaded from memory.

The NI-488.2 DLL might use the services of the virtual device driver, nivgpibd.386.

If you have more than 16 MB of RAM in your computer and you use DMA to read from

and write to your GPIB instrument, then you must have the nivgpibd.386device

installed. If it is not installed, the EDMA error might be returned.

You can remove the nivgpibd.386device by editing the system.inifile as

follows:

1. Locate the system.inifile in the Windows directory (usually c:\windows).

2. Find the line in the [386Enh] section that is of the following form:

device = drive:\path\nivgpibd.386

where drive is the drive (usually c) and path is the path where the NI-488.2

software is installed (for example, c:\at-gpibw).

3. Change this command line to a comment by adding a semicolon at the beginning of

the line as follows:

;device = drive:\path\nivgpibd.386

4. Restart Windows so that the change in system.inican take effect.

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Chapter 2

Application Examples

This chapter contains nine sample applications designed to illustrate specific GPIB

concepts and techniques that can help you write your own applications. The description

of each example includes the programmer's task, a program flowchart, and numbered

steps which correspond to the numbered blocks on the flowchart.

Use this chapter along with your NI-488.2 software, which includes the C and Visual

Basic source code for each of the nine examples. The programs are listed in order of

increasing complexity. If you are new to GPIB programming, you might want to study

the contents and concepts of the first sample, simple.c, before moving on to more

complex examples.

The following example programs are included with your NI-488.2 software:

• simple.c is the source code file for Example 1. It illustrates how you can establish

communication between a host computer and a GPIB device.

• clr_trg.cis the source code file for Example 2. It illustrates how you can clear

and trigger GPIB devices.

• asynch.c is the source code file for Example 3. It illustrates how you can perform

non-GPIB tasks while data is being transferred over the GPIB.

• eos.c is the source code file for Example 4. It illustrates the concept of the end-of-

string (EOS) character.

• rqs.c is the source code file for Example 5. It illustrates how you can communicate

with GPIB devices that use the GPIB SRQ line to request service. This sample is

written using NI-488 functions.

• easy4882.cis the source code file for Example 6. It is an introduction to NI-488.2

routines.

• rqs4882.cis the source code file for Example 7. It uses NI-488.2 routines to

communicate with GPIB devices that use the GPIB SRQ line to request service.

• ppoll.c is the source code file for Example 8. It uses NI-488.2 routines to conduct

parallel polls.

• non_cic.cis the source code file for Example 9. It illustrates how you can use the

NI-488.2 driver in a non-Controller application.

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Application Examples

Chapter 2

Example 1: Basic Communication

This example focuses on the basics of establishing communication between a host

computer and a GPIB device.

A technician needs to monitor voltage readings using a GPIB multimeter. His computer

is equipped with an IEEE 488.2 interface board. The NI-488.2 software is installed, and

a GPIB cable runs from the computer to the GPIB port on the multimeter.

The technician is familiar with the multimeter remote programming command set. This

list of commands is specific to his multimeter and is available from the multimeter

manufacturer.

He sets up the computer to direct the multimeter to take measurements and record each

measurement as it occurs. To do this, he has written an application that uses some simple

high-level GPIB commands. The following steps correspond to the program flowchart in

Figure 2-1.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application sends the multimeter an instruction, setting it up to take voltage

measurements in autorange mode.

3. The application sends the multimeter an instruction to take a voltage measurement.

4. The application tells the multimeter to transmit the data it has acquired to the

computer.

The process of requesting a measurement and reading from the multimeter (Steps 3

and 4) is repeated as long as there are readings to be obtained.

5. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

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2-2

Chapter 2

Application Examples

GPIB Cable

Computer

INIT

Multimeter

ibwrt

Set Up Multimeter

to Take Voltages

"VOLTS DC;AUTO"

"VOLTS?"

ibwrt

Tell Multimeter to

Take Measurement

ibrd

Read

Measurement

from Multimeter

"+ 5 volts"

Finished Getting

Measurements?

Yes

CLEAN UP

Figure 2-1. Program Flowchart for Example 1

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Application Examples

Chapter 2

Example 2: Clearing and Triggering Devices

This example illustrates how you can clear and trigger GPIB devices.

Two freshman physics lab partners are learning how to use a GPIB digital oscilloscope.

They have successfully loaded the NI-488.2 software on a personal computer and

connected their GPIB board to a GPIB digital oscilloscope. Their current lab assignment

is to write a small application to practice using the oscilloscope and its command set

using high-level GPIB commands. The following steps correspond to the program

flowchart in Figure 2-2.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application sends a GPIB clear command to the oscilloscope. This command

clears the internal registers of the oscilloscope, reinitializing it to default values and

settings.

3. The application sends a command to the oscilloscope telling it to read a waveform

each time it is triggered. Predefining the task in this way decreases the execution

time required. Each trigger of the oscilloscope is now sufficient to get a new run.

4. The application sends a GPIB trigger command to the oscilloscope which causes it to

acquire data.

5. The application queries the oscilloscope for the acquired data. The oscilloscope

sends the data.

6. The application reads the data from the oscilloscope.

7. The application calls an external graphics routine to display the acquired waveform.

Steps 4, 5, 6, and 7 are repeated until all of the desired data has been acquired by the

oscilloscope and received by the computer.

8. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

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2-4

Chapter 2

Application Examples

GPIB Cable

Computer

INIT

Oscilloscope

ibclr

Clear

Oscilloscope

Command

ibwrt

Define Task to Be Done

When Oscilloscope is

Triggered

"WAV=TRIG"

ibtrg

Trigger

Oscilloscope to

Get Reading

Trigger

Command

ibwrt

Request Data

from

"CURV?"

Data

Oscilloscope

ibrd

Read Data

from

Oscilloscope

Display

Waveform

Finished

Reading?

Yes

CLEAN UP

Figure 2-2. Program Flowchart for Example 2

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Application Examples

Chapter 2

Example 3: Asynchronous I/O

This example illustrates how an application conducts data transfers with a GPIB device

and immediately returns to perform other non-GPIB related tasks while GPIB I/O is

occurring in the background. This asynchronous mode of operation is particularly useful

when the requested GPIB activity may take some time to complete.

In this example, a research biologist is trying to obtain CAT scans of a laboratory

animal's liver. She will print out a color copy of each scan as it is acquired. The entire

operation is computer-controlled. The CAT scan machine sends the images it acquires to

a computer that has the NI-488.2 software installed and is connected to a GPIB color

printer . The biologist is familiar with the command set of her color printer, as described

in the color printer's user manual. She acquires and prints images with the aid of an

application program she wrote using high-level GPIB commands. The following steps

correspond to the program flowchart in Figure 2-3.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. An image is scanned in.

3. The application sends the GPIB printer a command to print the new image and

immediately returns without waiting for the I/O operation to be completed.

4. The application saves the image obtained to a file.

5. The application inquires as to whether the printing operation has completed by

issuing a GPIB wait command. If the status reported by the wait command indicates

completion (CMPL is in the status returned) and more scans need to be acquired,

Steps 2 through 5 are repeated until the scans have all been acquired. If the status

reported by the wait command in Step 5 does not indicate that printing is finished,

statistical computations are performed on the scan obtained and Step 5 is repeated.

6. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

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2-6

Chapter 2

Application Examples

GPIB Cable

Computer

INIT

Color Printer

Image

Scan

ibwrta

Print Image

Asynchronously

Non-GPIB

Activity: Save

to Disk

ibwait

Is GPIB

Printing

Done?

Non-GPIB Activity:

Compute Statistics

Yes

Images?

CLEAN UP

Figure 2-3. Program Flowchart for Example 3

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Application Examples

Chapter 2

Example 4: End-of-String Mode

This example illustrates how to use the end-of-string modes to detect that the GPIB

device has finished sending data.

A journalist is using a GPIB scanner to scan some pictures into his personal computer for

a news story. A GPIB cable runs between the scanner and the computer. He is using an

application written by an intern in the department who has read the scanner's instruction

manual and is familiar with the scanner's programming requirements. The following

steps correspond to the program flowchart in Figure 2-4.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application sends a GPIB clear message to the scanner, initializing it to its

power-on defaults.

3. The scanner needs to detect a delimiter indicating the end of a command. In this

case, the scanner expects the commands to be terminated with <CR><LF> (carriage

return, \r, and linefeed, \n). The application sets its end-of-string (EOS) byte to

<LF>. The linefeed code indicates to the scanner that no more data is coming, and is

called the end-of-string byte. It flags an end-of-string condition for this particular

GPIB scanner. The same effect could be accomplished by asserting the EOI line

when the command is sent.

4. With the exception of the scan resolution, all the default settings are appropriate for

the task at hand. The application changes the scan resolution by writing the

appropriate command to the scanner.

5. The scanner sends back information describing the status of the change resolution

command. This is a string of bytes terminated by the end-of-string character to tell

the application it is done changing the resolution.

6. The application starts the scan by writing the scan command to the scanner.

7. The application reads the scan data into the computer.

8. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

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2-8

Chapter 2

Application Examples

GPIB Cable

Scanner

Computer

INIT

ibclr

Reset

Internal

State

Clear

Command

ibeos

Set EOS

Mode

ibwrt

Change

Scan

"RES:3 \ r \ n"

"OK"

Resolution

ibrd

Read Status

ibwrt

Start Scan

"scan \ r \ n"

ibrd

Read

Data

Scanned

Data

CLEAN UP

Figure 2-4. Program Flowchart for Example 4

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Application Examples

Chapter 2

Example 5: Service Requests

This example illustrates how an application communicates with a GPIB device that uses

the GPIB service request (SRQ) line to indicate that it needs attention.

A graphic arts designer is transferring digital images stored on her computer to a roll of

color film, using a GPIB digital film recorder. A GPIB cable connects the GPIB port on

the film recorder to the IEEE 488.2 interface board installed in her computer. She has

installed the NI-488.2 software on the host computer and is familiar with the

programming instructions for the film recorder, as described in the film recorder's user

manual. She places a fresh roll of film in the camera and launches a simple application

she has written using high-level GPIB commands. With the aid of the application, she

records a few images on film. The following steps correspond to the program flowchart

in Figure 2-5.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application brings the film recorder to a ready state by issuing a device clear

instruction. The film recorder is now set up for operation using its default values.

(The graphic arts designer has previously established that the default values for the

film recorder are appropriate for the type of film she is using.)

3. The application advances the new roll of film into position so the first image can be

exposed on the first frame of film. This is done by sending the appropriate

instructions as described in the film recorder programming guide.

4. The application waits for the film recorder to signify that it is done loading the film,

by waiting for RQS (request for service). The film recorder asserts the GPIB SRQ

line when it has finished loading the film.

5. As soon as the film recorder asserts the GPIB SRQ line, the application’s wait for the

RQS event completes. The application conducts a serial poll by sending a special

command message to the film recorder that directs it to return a response in the form

of a serial poll status byte. This byte contains information indicating what kind of

service the film recorder is requesting or what condition it is flagging. In this

example, it indicates the completion of a command.

6. A color image transfers to the digital film recorder in three consecutive passes–one

pass each for the red, green and blue components of the image. Sub-steps 6a, 6b,

and 6c are repeated for each of the passes:

6a. The application sends a command to the film recorder directing it to accept data

to create a single pass image. The film recorder asserts the SRQ line as soon as

a pass is completed.

6b. The application waits for RQS.

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2-10

Chapter 2

Application Examples

6c. When the SRQ line is asserted, the application serial polls the film recorder to

see if it requested service, as in Step 5.

7. The application issues a command to the film recorder to advance the film by one

frame. The advance occurs successfully unless the end of film is reached.

8. The application waits for RQS, which completes when the film recorder asserts the

SRQ line to signal it is done advancing the film.

9. As soon as the application's wait for RQS completes, the application serial polls the

film recorder to see if it requested service, as in Step 5. The returned serial poll

status byte indicates either of two conditions–the film recorder finished advancing

the film as requested or the end of film was reached and it can no longer advance.

Steps 6 through 9 are repeated as long as film is in the camera and more images need

to be recorded.

10. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

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NI-488.2 User Manual for Windows

Application Examples

Chapter 2

GPIB Cable

Digital Film Recorder

Computer

INIT

ibclr

Clear Film Recorder

Clear Command

ibwrt

Advance

Film

"FRM+"

ibwait

Request

Service

Wait for the

Film Recorder to

Request Service

Did You Request

Service ?

Yes

ibrsp

Read

Response from

the Film

Response

Recorder

Finished

Film?

Exit Application

and Repair

Film Recorder

Yes

(continues)

Figure 2-5. Program Flowchart for Example 5

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2-12

Chapter 2

Application Examples

(Continued)

Digital Film Recorder

Computer

Yes

ibwrt

Create a

Single Pass

Image

Data for Red, Green,

or Blue Pass

ibwait

These steps

are repeated 3

times, once for

each color

pass

Request

Service

Wait for Film

Recorder to

Request

Did You Request

Service?

Service

Yes

ibrsp

Read Response

From Film

Response

Recorder

ibwrt

"ADV"

Advance Film

ibwait

Request

Service

Wait for Film

Recorder to

Request

Did You Request

Service?

Service

Yes

ibrsp

Read Response From

Film Recorder

Response

Reached

End of

Film?

Yes

CLEAN UP

Figure 2-5. Program Flowchart for Example 5 (Continued)

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NI-488.2 User Manual for Windows

Application Examples

Chapter 2

Example 6: Basic Communication with

IEEE 488.2-Compliant Devices

This example is an introduction to communicating with IEEE 488.2-compliant devices.

A test engineer in a metal factory is using IEEE 488.2-compliant tensile testers to

determine the strength of metal rods as they come out of production. There are several

tensile testers and they are all connected to a central computer equipped with an IEEE

488.2 interface board. These machines are fairly voluminous and it is difficult for the

engineer to reach the address switches of each machine. For the purposes of his future

work with these tensile testers, he needs to determine the setting of each GPIB address

switch. He can do so with the aid of a simple application he has written. The following

steps correspond to the program flowchart in Figure 2-6.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application issues a command to detect the presence of listening devices on the

GPIB and compiles a list of the addresses of all such devices.

3. The application sends an identification query ("*IDN?") to all of the devices

detected on the GPIB in Step 2.

4. The application reads the identification information returned by each of the devices

as it responds to the query in Step 3.

5. As a cleanup step before exiting, the application returns the interface board back to

its original state by taking it offline.

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2-14

Chapter 2

Application Examples

GPIB Cable

Tensile Tester 3

Computer

INIT

Tensile Tester 1 Tensile Tester 2

FindLstn

Who's

Listening?

Get a List

of Devices

Present on

GPIB

Device 1

is Here

Device 2

is Here

Device 3

is Here

Send

Tell Device 1

to Identify

Itself

"*IDN?"

Receive

Read

Response

from

"MUTT 10383"

Device 1

Send

Tell Device

2 to Identify

Itself

"*IDN?"

Receive

Read

Response

from

"MUTT 10426"

Device 2

Send

Tell Device

3 to Identify

Itself

"*IDN?"

Receive

Read

Response

from

"MUTT 10528"

Device 3

CLEAN UP

Figure 2-6. Program Flowchart for Example 6

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NI-488.2 User Manual for Windows

Application Examples

Chapter 2

Example 7: Serial Polls Using NI-488.2 Routines

This example illustrates how you can take advantage of the NI-488.2 routines to reduce

the complexity of performing serial polls of multiple devices.

A candy manufacturer is using GPIB strain gauges to measure the consistency of the

syrup used to make candy. The plant has four big mixers containing syrup. The syrup

has to reach a certain consistency to make good quality candy. This is measured by strain

gauges that monitor the amount of pressure used to move the mixer arms. When a certain

consistency is reached, the mixture is removed and a new batch of syrup is poured in the

mixer. The GPIB strain gauges are connected to a computer with an IEEE 488.2

interface board and the NI-488.2 software installed. The process is controlled by an

application that uses NI-488.2 routines to communicate with the IEEE 488.2-compliant

strain gauges. The following steps correspond to the program flowchart in Figure 2-7.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application configures the strain gauges to request service when they have a

significant pressure reading or a mechanical failure occurs. They signal their request

for service by asserting the SRQ line.

3. The application waits for one or more of the strain gauges to indicate that they have a

significant pressure reading. This wait event ends as soon as the SRQ line is

asserted.

4. The application serial polls each of the strain gauges to see if it requested service.

5. Once the application has determined which one of the strain gauges requires service,

it takes a reading from that strain gauge.

6. If the reading matches the desired consistency, a dialog window appears on the

computer screen and prompts the mixer operator to remove the mixture and start a

new batch. Otherwise, a dialog window prompts the operator to service the mixer in

some other way.

Steps 3 through 6 are repeated as long as the mixers are in operation.

7. After the last batch of syrup has been processed, the application returns the interface

board to its original state by taking it offline.

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2-16

Chapter 2

Application Examples

GPIB Cable

Strain

Gauge 2

Strain

Gauge 3

Computer

INIT

Strain

Gauge 1

SendList

Configure Strain

Gauges to

"SRQ=HI"

Request Service

When They

Have a Reading

WaitSRQ

Wait for 1 or More

Strain Gauges to

Request Service

Request

Service

FindRQS

Did You Request

Serial Poll Each

Strain Gauge

Until One

Requesting

Service is

Located

Service?

Did You Request

Service?

Yes

Receive

Get a Reading

From Strain

Gauge

Response

Does the

Gauge Need

Service?

Yes

Provide

Whatever

Service is

Required

Mixture is Ready.

Display "Remove

Mixture"

Message

Done for

the

Day?

Yes

CLEAN UP

Figure 2-7. Program Flowchart for Example 7

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NI-488.2 User Manual for Windows

Application Examples

Chapter 2

Example 8: Parallel Polls

This example illustrates how you can use NI-488.2 routines to obtain information from

several IEEE 488.2-compliant devices at once using a procedure called parallel polling.

The process of manufacturing a particular alloy involves bringing three different metals

to specific temperatures before mixing them to form the alloy. Three vats are used, each

containing a different metal. Each is monitored by a GPIB ore monitoring unit. The

monitoring unit consists of a GPIB temperature transducer and a GPIB power supply.

The temperature transducer is used to probe the temperature of each metal. The power

supply is used to start a motor to pour the metal into the mold when it reaches a

predefined temperature. The three monitoring units are connected to the IEEE 488.2

interface board of a computer that has the NI-488.2 software installed. An application

using NI-488.2 routines operates the three monitoring units. The application will obtain

information from the multiple units by conducting a parallel poll, and will then determine

when to pour the metals into the mixture tank. The following steps correspond to the

program flowchart in Figure 2-8.

1. The application initializes the GPIB by bringing the interface board in the computer

online.

2. The application configures the temperature transducer in the first monitoring unit by

choosing which of the eight GPIB data lines the transducer uses to respond when a

parallel poll is conducted. The application also sets the temperature threshold. The

transducer manufacturer has defined the individual status (ist) bit to be true when

the temperature threshold is reached, and the configured status mode of the

transducer is assert the data line. When a parallel poll is conducted, the transducer

asserts its data line if the temperature has exceeded the threshold.

3. The application configures the temperature transducer in the second monitoring unit

for parallel polls.

4. The application configures the temperature transducer in the third monitoring unit for

parallel polls.

5. The application conducts non-GPIB activity while the metals are heated.

6. The application conducts a parallel poll of all three temperature transducers to

determine whether the metals have reached the appropriate temperature. Each

transducer asserts its data line during the configuration step if its temperature

threshold has been reached.

7. If the response to the poll indicates that all three metals are at the appropriate

temperature, the application sends a command to each of the three power supplies,

directing them to power on. Then the motors start and the metals pour into the mold.

If only one or two of the metals is at the appropriate temperature, Steps 5 and 6 are

repeated until the metals can be successfully mixed.

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2-18

Chapter 2

Application Examples

8. The application unconfigures all of the transducers so that they no longer participate

in parallel polls.

9. As a cleanup step before exiting, the application returns the interface board to its

original state by taking it offline.

GPIB

Cable

GPIB

Cable

GPIB

Cable

GPIB

Cable

GPIB

Cable

GPIB Cable

Computer

UNIT 1

UNIT 2

UNIT 3

Temp

Power

Supply

Temp

Power

Temp

Power

Transducer

Transducer Supply

INIT

PPollConfig

Configure

Transducer 1 for

Parallel Polls

Parallel Poll

Enable

PPollConfig

Configure

Transducer 2

for Parallel Polls

Parallel Poll

Enable

PPollConfig

Configure

Transducer 3

for Parallel Polls

Parallel Poll

Enable

Non-GPIB

Activity

PPoll

Parallel Poll

Are All

Metals

Ready?

Yes

SendList

"MIX ON"

Start Power

Supplies

PPollUnconfig

PPoll

Parallel Poll

Disable

Unconfigure

CLEAN UP

Figure 2-8. Program Flowchart for Example 8

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NI-488.2 User Manual for Windows

Application Examples

Chapter 2

Example 9: Non-Controller Example

This example illustrates how you can use the NI-488.2 software to emulate a GPIB

device that is not the GPIB Controller.

A software engineer has written firmware to emulate a GPIB device for a research project

and is testing it using an application that makes simple GPIB calls. The following steps

correspond to the program flowchart in Figure 2-9.

1. The application brings the device online.

2. The application waits for any of three events to occur: the device to become listen-

addressed, become talk-addressed, or receive a GPIB clear message.

3. As soon as one of the events occurs, the application takes an action based upon the

event that occurred. If the device was cleared, the application resets the internal state

of the device to default values. If the device was talk-addressed, it writes data back

to the Controller. If the device was listen-addressed, it reads in new data from the

Controller.

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Application Examples

Device

INIT

Controller

ibwait

Wait to be Talk

Addressed,

Listen

Addressed, or

Cleared

fffffffffff

Reset

Internal

State

Is This the

Clear Event?

Yes

Is This the

Talk

Addressed

Event?

Yes

ibwrt

Write Out

New Data

Data

ibrd

Read In

New Data

Figure 2-9. Program Flowchart for Example 9

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NI-488.2 User Manual for Windows

Chapter 3

Developing Your Application

This chapter explains how to develop a GPIB application program using NI-488

functions and NI-488.2 routines.

Choosing How to Access the NI-488.2 DLL

Applications can access the NI-488.2 dynamic link library (gpib.dll) either by using

the NI-488.2 language interfaces for C or Visual Basic, or by directly accessing the

gpib.dll. The NI-488.2 language interface is the easiest and fastest method, and it is

adequate for most applications.

If you want to access the gpib.dll from languages other than C and Visual Basic, or if

you have special needs for accessing the gpib.dll, then you must use the direct entry

functions. These functions are identical to the NI-488 and NI-488.2 calls, except for the

following two differences:

•

You must preface each function name by the characters DLL. For example, instead of

using the NI-488 function ibwrt, use the direct entry function DLLibwrt.

•

The number of arguments taken by each function is increased by three. The last three

parameters are, in order, a pointer to the ibsta variable, a pointer to the iberr

variable, and a pointer to the ibcntl variable. Your application must declare its

own ibsta, iberr, and ibcntl variables to use the direct entry functions.

Choosing Between NI-488 Functions and NI-488.2 Routines

Your NI-488.2 software includes two distinct sets of subroutines to meet your application

needs. For most application programs, the NI-488 functions are sufficient. You should

use the NI-488.2 routines if you have a complex configuration with one or more interface

boards and multiple devices.

The following sections discuss some differences between NI-488 functions and NI-488.2

routines.

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Developing Your Application

Chapter 3

Using NI-488 Functions: One Device for Each Board

If your system has only one device attached to each board, the NI-488 functions are

probably sufficient for your programming needs. Some other factors that make the

NI-488 functions more convenient include the following:

•

With NI-488 asynchronous I/O functions (ibcmda, ibrda, and ibwrta), you can

initiate an I/O sequence while maintaining control over the CPU for non-GPIB tasks.

•

NI-488 functions include built-in file transfer functions (ibrdf and ibwrtf).

With NI-488 functions, you can control the bus in non-typical ways or communicate

with non-compliant devices.

The NI-488 functions consist of high-level (or device) functions that hide much of the

GPIB management operations and low-level (or board) functions that offer you more

control over the GPIB than NI-488.2 routines. The following sections describe these

different function types.

NI-488 Device Functions

Device functions are high-level functions that automatically execute commands that

handle bus management operations such as reading from and writing to devices or polling

them for status. If you use device functions, you do not need to understand GPIB

protocol or bus management. For information about device-level calls and how they

manage the GPIB, refer to Device-Level Calls and Bus Management, in Chapter 7, GPIB

Programming Techniques.

NI-488 Board Functions

Board functions are low-level functions that perform rudimentary GPIB operations.

Board functions access the interface board directly and require you to handle the

addressing and bus management protocol. In cases when the high-level device functions

might not meet your needs, low-level board functions give you the flexibility and control

to handle situations such as the following:

•

Communicating with non-compliant (non-IEEE 488.2) devices

Altering various low-level board configurations

Managing the bus in non-typical ways

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Chapter 3

Developing Your Application

The NI-488 board functions are compatible with, and can be interspersed within,

sequences of NI-488.2 routines. When you use board functions within a sequence of

NI-488.2 routines, you do not need a prior call to ibfind to obtain a board descriptor.

You simply substitute the board index as the first parameter of the board function call.

With this flexibility, you can handle non-standard or unusual situations that you cannot

resolve using NI-488.2 routines only.

Using NI-488.2 Routines: Multiple Boards and/or Multiple Devices

When your system includes a board that must access more than one device, use the

NI-488.2 routines. NI-488.2 routines can perform the following tasks with a single call:

•

Find all of the Listeners on the bus

Find a device requesting service

Determine the state of the SRQ line, or wait for SRQ to be asserted

Address multiple devices to listen

Checking Status with Global Variables

Each NI-488 function and NI-488.2 routine updates the global variables to reflect the

status of the device or board that you are using. The status word (ibsta), the error

variable (iberr), and the count variables (ibcnt and ibcntl) contain useful

information about the performance of your application program. Your program should

check these variables frequently. The following sections describe each of these global

variables and how you can use them in your application program.

Status Word – ibsta

All functions update a global status word, ibsta, which contains information about the

state of the GPIB and the GPIB hardware. Most of the NI-488 functions return the value

stored in ibsta. You can test for conditions reported in ibstato make decisions

about continued processing, or you can debug your program by checking ibstaafter

each call.

ibsta is a 16-bit value. A bit value of one (1) indicates that a certain condition is in

effect. A bit value of zero (0) indicates that the condition is not in effect. Each bit in

ibsta can be set for NI-488 device calls (dev), NI-488 board calls and NI-488.2 calls

(brd), or all (dev, brd).

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Developing Your Application

Chapter 3

Table 3-1 shows the condition that each bit position represents, the bit mnemonics, and

the type of calls for which each bit can be set. For a detailed explanation of each of the

status conditions, refer to Appendix A, Status Word Conditions.

Table 3-1. Status Word (ibsta) Layout

Bit

Pos.

Hex

Value

Mnemonic

ERR

Type

dev, brd

brd

Description

8000

4000

2000

1000

800

GPIB error

TIMO

END

Time limit exceeded

END or EOS detected

SRQ interrupt received

Device requesting service

SRQI

RQS

dev

SPOLL

400

brd

Board has been serial polled by

Controller

EVENT

CMPL

LOK

200

100

brd

dev, brd

brd

DCAS, DTAS, or IFC event has occurred

I/O completed

Lockout State

REM

brd

Remote State

CIC

brd

Controller-In-Charge

Attention is asserted

Talker

ATN

brd

TACS

LACS

DTAS

DCAS

brd

Listener

brd

Device Trigger State

Device Clear State

brd

The language header files included on your distribution disk contain the mnemonic

constants for ibsta. You can check a bit position in ibstaby using its numeric value

or its mnemonic constant. For example, bit position 15 (hex 8000) detects a GPIB error.

The mnemonic for this bit is ERR. To check for a GPIB error, use either of the following

statements after each NI-488 function and NI-488.2 routine as shown:

if (ibsta & ERR) gpiberr();

if (ibsta & 0x8000) gpiberr();

where gpiberr()is an error handling routine.

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Developing Your Application

Error Variable – iberr

If the ERR bit is set in the status word (ibsta), a GPIB error has occurred. When an

error occurs, the error type is specified by the value in iberr.

Note: The value in iberris meaningful as an error type only when the ERR bit is

set, indicating that an error has occurred.

For more information on error codes and solutions refer to Chapter 4, Debugging Your

Application, or Appendix B, Error Codes and Solutions.

Count Variables – ibcnt and ibcntl

The count variables are updated after each read, write, or command function. ibcntis a

16-bit integer and ibcntl is a 32-bit integer. If you are reading data, the count

variables indicate the number of bytes read. If you are sending data or commands, the

count variables reflect the number of bytes sent.

In your application program, you can use the count variables to null-terminate an ASCII

string of data received from an instrument. For example, if data is received in an array of

characters, you can use ibcntlto null-terminate the array and print the measurement on

the screen as follows:

char rdbuf[512];

ibrd (ud, rdbuf, 20L);

if (!(ibsta & ERR)){

rdbuf[ibcntl] = '\0';

printf ("Read: %s\n", rdbuf);

}

else {

error();

}

ibcntl is the number of bytes received. Data begins in the array at index zero (0);

therefore, ibcntlis the position for the null character that marks the end of the string.

Using wibic to Communicate with Devices

Before you begin writing your application program, you might want to use the wibic

utility. With wibic (Windows Interface Bus Interactive Control), you communicate

with your instruments from the keyboard rather than from an application program. You

can use wibicto learn to communicate with your instruments using the NI-488

functions or NI-488.2 routines. For specific device communication instructions, refer to

the user manual that came with your instrument. For information about using wibic

and for detailed examples, refer to Chapter 5, wibic–Windows Interface Bus Interactive

Control Utility.

After you have learned how to communicate with your devices in wibic, you are ready

to begin writing your application program.

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Developing Your Application

Chapter 3

Writing Your NI-488 Application

This section discusses items you should include in your application program, general

program steps, and an NI-488 example. In this manual the example code is presented in

C. The NI-488.2 software includes the source code for C (devsamp.c), Visual Basic

(devsamp.bas), direct entry functions in C (dlldev.c), and direct entry functions in

Visual Basic (dlldev.bas).

The NI-488.2 software also includes the source code for nine application examples,

which are described in Chapter 2, Application Examples.

Items to Include

•

Include the appropriate GPIB header file. This file contains prototypes for the NI-488

functions and constants that you can use in your application program.

•

Check for errors after each NI-488 function call.

Declare and define a function to handle GPIB errors. This function takes the device

offline and closes the application. If the function is declared as:

void gpiberr (char * msg); /* function prototype */

then your application invokes it as follows:

if (ibsta & ERR) {

gpiberr ("GPIB error");

}

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Chapter 3

Developing Your Application

NI-488 Program Shell

Figure 3-1 is a flowchart of the steps to create your application program using device-

level NI-488 functions.

START

Open Device (ibdev)

Are All

Devices

Open?

Yes

Make a Device-Level Call

• Send Data to Device

(ibwrt)

(ibrd)

• Receive Data from Device

• Clear Device

(ibclr)

(ibrsp)

• Serial Poll Device

and so on

Finished GPIB

Programming?

Yes

Close Device (ibonl)

Closed All

Devices?

Yes

END

Figure 3-1. General Program Shell Using NI-488 Device Functions

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Developing Your Application

Chapter 3

General Program Steps and Examples

The following steps demonstrate how to use the NI-488 device functions in your

program. This example configures a digital multimeter, reads 10 voltage measurements,

and computes the average of these measurements.

Step 1. Open a Device

Your first NI-488 function call should be to ibdevto open a device.

ud = ibdev(0, 1, 0 , T10s, 1, 0);

if (ibsta & ERR) {

gpiberr("ibdev error");

}

The input arguments of the ibdev function are as follows:

0 - board index for GPIB0

1 - primary GPIB address of the device

0 - no secondary GPIB address for the device

T10s - I/O timeout value (10 s)

1 - send END message with the last byte when writing to device

0 - disable EOS detection mode

When you call ibdev, the driver automatically initializes the GPIB by sending an

Interface Clear (IFC) message and placing the device in remote programming state.

Step 2. Clear the Device

Clear the device before you configure the device for your application. Clearing the

device resets its internal functions to a default state.

ibclr(ud);

if (ibsta & ERR) {

gpiberr("ibclr error");

}

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Developing Your Application

Step 3. Configure the Device

After you open and clear the device, it is ready to receive commands. To configure the

instrument, you send device-specific commands using the ibwrt function. Refer to the

instrument user manual for the command bytes that work with your instrument.

ibwrt(ud, "*RST; VAC; AUTO; TRIGGER 2; *SRE 16", 35L);

if (ibsta & ERR) {

gpiberr("ibwrt error");

}

The programming instruction in this example resets the multimeter (*RST). The meter is

instructed to measure the volts alternating current (VAC) using auto-ranging (AUTO), to

wait for a trigger from the GPIB interface board before starting a measurement

(TRIGGER 2), and to assert the SRQ line when the measurement completes and the

multimeter is ready to send the result (*SRE 16).

Step 4. Trigger the Device

If you configure the device to wait for a trigger, you must send a trigger command to the

device before reading the measurement value. Then instruct the device to send the next

triggered reading to its GPIB output buffer.

ibtrg(ud);

if (ibsta & (ERR 1 TIMO)) {

gpiberr("ibtrg error");

}

ibwrt(ud,"VAL1?", 5L);

if (ibsta & ERR) {

gpiberr("ibwrt error");

}

Step 5. Wait for the Measurement

After you trigger the device, the RQS bit is set when the device is ready to send the

measurement. You can detect RQS by using the ibwait function. The second

parameter indicates what you are waiting for. Notice that the ibwait function also

returns when the I/O timeout value is exceeded.

printf("Waiting for RQS...\n");

ibwait (ud, TIMO| RQS);

if (ibsta & (ERR | TIMO)) {

gpiberr("ibwait error");

}

When SRQ has been detected, serial poll the instrument to determine if the measured data

is valid or if a fault condition exists. For IEEE 488.2 instruments, you can find out by

checking the message available (MAV) bit, bit 4 in the status byte that you receive from

the instrument.

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Developing Your Application

Chapter 3

ibrsp (ud, &StatusByte);

if (ibsta & ERR) {

gpiberr("ibrsp error");

}

if ( !(StatusByte & MAVbit)) {

gpiberr("Improper Status Byte");

printf(" Status Byte = 0x%x\n", StatusByte);

}

Step 6. Read the Measurement

If the data is valid, read the measurement from the instrument. (AsciiToFloatis a

function that takes a null-terminated string as input and outputs the floating point number

it represents.)

ibrd (ud, rdbuf, 10L);

if (ibsta & ERR) {

gpiberr("ibrd error");

}

rdbuf[ibcntl] = '\0';

printf("Read: %s\n", rdbuf);

/* Output ==> Read: +10.98E-3 */

sum += AsciiToFloat(rdbuf);

Step 7. Process the Data

Repeat steps 4 through 6 in a loop until 10 measurements have been read. Then print the

average of the readings as shown:

printf("The average of the 10 readings is %f\n", sum/10.0);

Step 8. Place the Device Offline

As a final step, take the device offline using the ibonl function.

ibonl (ud, 0);

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Chapter 3

Developing Your Application

Writing Your NI-488.2 Application

This section discusses items you should include in an application program that uses

NI-488.2 routines, general program steps, and an NI-488.2 example. In this manual the

example code is presented in C. The NI-488.2 software includes the source code for C

(samp4882.c), Visual Basic (samp4882.bas), direct entry functions in C

(dll4882.c), and direct entry functions in Visual Basic (dll4882.bas).

The NI-488.2 software also includes the source code for nine example programs, which

are described in Chapter 2, Application Examples.

Items to Include

•

Include the appropriate GPIB header file. This file contains prototypes for the

NI-488.2 routines and constants that you can use in your application program.

•

Check for errors after each NI-488.2 routine.

Declare and define a function to handle GPIB errors. This function takes the device

offline and closes the application. If the function is declared as:

void gpiberr (char * msg); /* function prototype */

then your application invokes it as follows:

if (ibsta & ERR) {

gpiberr ("GPIB error");

}

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NI-488.2 User Manual for Windows

Developing Your Application

Chapter 3

NI-488.2 Program Shell

Figure 3-2 is a flowchart of the steps to create your application program using NI-488.2

routines.

START

Initialize Specified GPIB

Interface (SendIFC)

Are All Boards

Initialized?

Yes

Making

Low-Level

High-Level

High-Level or

Low-Level Call?

Make a Low-Level Call

Make a High-Level Call

• Send Data to Device (Send)

• Receive Data from Device

(Receive)

• Clear Device (DevClear)

• Serial Poll Device

(ReadStatusByte)

and so on

• Address Devices to Listen (SendSetup)

• Send Data to Addressed Listener

(SendDataBytes)

• Address Device to Talk (ReceiveSetup)

• Receive Data from Addressed Talker

(RcvRespMsg)

and so on

Finished GPIB

Programming?

Yes

Close Board

(ibonl)

Are All Boards

Closed?

Yes

END

Figure 3-2. General Program Shell Using NI-488.2 Routines

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Chapter 3

Developing Your Application

General Program Steps and Examples

The following steps demonstrate how to use the NI-488.2 routines in your program. This

example configures a digital multimeter, reads 10 voltage measurements, and computes

the average of these measurements.

Step 1. Initialization

Use the SendIFC routine to initialize the bus and the GPIB interface board so that the

GPIB board is Controller-In-Charge (CIC). The only argument of SendIFCis the GPIB

interface board number.

SendIFC(0);

if (ibsta & ERR) {

gpiberr("SendIFC error");

}

Step 2. Find All Listeners

Use the FindLstn routine to create an array of all of the instruments attached to the

GPIB. The first argument is the interface board number, the second argument is the list

of instruments that was created, the third argument is a list of instrument addresses that

the procedure actually found, and the last argument is the maximum number of devices

that the procedure can find (that is, it must stop if it reaches the limit). The end of the list

of addresses must be marked with the NOADDR constant, which is defined in the header

file that you included at the beginning of the program.

for (loop = 0; loop <=30; loop++){

instruments[loop] = loop;

}

instruments[31] = NOADDR;

printf("Finding all Listeners on the bus...\n");

Findlstn(0, instruments, result, 30);

if (ibsta & ERR) {

gpiberr("FindLstn error");

}

Step 3. Identify the Instrument

Send an identification query to each device for identification. For this example, assume

that all of the instruments are IEEE 488.2-compatible and can accept the identification

query, *IDN?. In addition, assume that FindLstn found the GPIB interface board at

primary address 0 (default) and, therefore, you can skip the first entry in the result

array.

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Developing Your Application

Chapter 3

for (loop = 1; loop <= num_Listeners; loop++) {

Send(0, result[loop], "*IDN?", 5L, NLend);

if (ibsta & ERR) {

gpiberr("Send error");

}

Receive(0, result[loop], buffer, 10L, STOPend);

if (ibsta & ERR) {

gpiberr("Receive error");

}

buffer[ibcntl] = '\0';

printf("The instrument at address %d is a %s\n",

result[loop], buffer);

if (strncmp(buffer, "Fluke, 45", 9) == 0) {

fluke = result[loop];

printf("**** Found the Fluke ****\n");

break;

}

if (loop > num_Listeners) {

printf("Did not find the Fluke!\n");

ibonl(0,0);

exit(1);

}

The constant NLend signals that the new line character with EOI is automatically

appended to the data to be sent.

The constant STOPend indicates that the read is stopped when EOI is detected.

Step 4. Initialize the Instrument

After you find the multimeter, use the DevClearroutine to clear it. The first argument

is the GPIB board number. The second argument is the GPIB address of the multimeter.

Then send the IEEE 488.2 reset command to the meter.

DevClear(0, fluke);

if (ibsta & ERR) {

gpiberr("DevClear error")

}

Send(0, fluke, "*RST", 4L, NLend);

if (ibsta & ERR) {

gpiberr("Send *RST error");

}

sum = 0.0;

for(m =0; m<10; m++){

/* start of loop for Steps 5 through 8 */

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Chapter 3

Developing Your Application

Step 5. Configure the Instrument

After initialization, the instrument is ready to receive instructions. To configure the

multimeter, use the Sendroutine to send device-specific commands. The first argument

is the number of the access board. The second argument is the GPIB address of the

multimeter. The third argument is a string of bytes to send to the multimeter.

The bytes in this example instruct the meter to measure volts alternating current (VAC)

using auto-ranging (AUTO), to wait for a trigger from the Controller before starting a

measurement (TRIGGER 2), and to assert SRQ when the measurement has been

completed and the meter is ready to send the result (*SRE 16). The fourth argument

represents the number of bytes to be sent. The last argument, NLend, is a constant

defined in the header file which tells Send to append a linefeed character, with EOI

asserted, to the end of the message sent to the multimeter.

Send (0,fluke,"VAC; AUTO; TRIGGER 2; *SRE 16", 29L, NLend);

if (ibsta & ERR) {

gpiberr("Send setup error");

}

Step 6. Trigger the Instrument

In the previous step, the multimeter was instructed to wait for a trigger before conducting

a measurement. Now send a trigger command to the multimeter. You could use the

Trigger routine to accomplish this, but because the Fluke 45 is IEEE 488.2-

compatible, you can just send it the trigger command, *TRG. The VAL1?command

instructs the meter to send the next triggered reading to its output buffer.

Send(0, fluke, "*TRG; VAL1?", 11L, NLend);

if (ibsta & ERR) {

gpiberr("Send trigger error");

}

Step 7. Wait for the Measurement

After the meter is triggered, it takes a measurement and displays it on its front panel and

then asserts SRQ. You can detect the assertion of SRQ using either the TestSRQor

WaitSRQ routine. If you have a process that you want to execute while you are waiting

for the measurement, use TestSRQ. For this example, you can use the WaitSRQ

routine. The first argument in WaitSRQis the GPIB board number. The second

argument is a flag returned by WaitSRQ that indicates whether or not SRQ is asserted.

WaitSRQ(0, &SRQasserted);

if (!SRQasserted) {

gpiberr("WaitSRQ error");

}

After you have detected SRQ, use the ReadStatusByteroutine to poll the meter and

determine its status. The first argument is the GPIB board number, the second argument

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Developing Your Application

Chapter 3

is the GPIB address of the instrument, and the last argument is a variable that

ReadStatusByteuses to store the status byte of the instrument.

ReadStatusByte(0, fluke, &statusByte);

if (ibsta & ERR) {

gpiberr("ReadStatusByte error");

}

After you have obtained the status byte, you must check to see if the meter has a message

to send. You can do this by checking the message available (MAV) bit, bit 4 in the status

byte.

if (!(statusByte & MAVbit) {

gpiberr("Improper Status Byte");

printf("Status Byte = 0x%x\n", statusByte);

}

Step 8. Read the Measurement

Use the Receive function to read the measurement over the GPIB. The first argument

is the GPIB interface board number, and the second argument is the GPIB address of the

multimeter. The third argument is a string into which the Receivefunction places the

data bytes from the multimeter. The fourth argument represents the number of bytes to

be received. The last argument indicates that the Receivemessage terminates upon

receiving a byte accompanied with the END message.

Receive(0, fluke, buffer, 10L, STOPend);

if (ibsta & ERR) {

gpiberr("Receive error");

}

buffer[ibcntl] = '\0';

printf (Reading : %s\n", buffer);

sum += AsciiToFloat(buffer);

} /* end of loop started in Step 5 */

Step 9. Process the Data

Repeat Steps 5 through 8 in a loop until 10 measurements have been read. Then print the

average of the readings as shown:

printf(" Theaverageof the10 readingsis : %f\n",sum/10);

Step 10. Place the Board Offline

Before ending your application program, take the board offline using the ibonl

function.

ibonl(0,0);

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Chapter 3

Developing Your Application

Compiling, Linking, and Running Your Application

The following sections describe how to compile, link, and run your application program.

To see examples that show how to include specific lines of code in your program, refer to

the program examples included with your NI-488.2 software.

If you discover errors when you execute the program refer to Chapter 4, Debugging Your

Application. If you want to verify the NI-488 and NI-488.2 calls made by your

application, you can use GPIB Spy, the GPIB applications monitor for Windows

described in Chapter 6, GPIB Spy.

Microsoft C

Before you compile your C application program, make sure that the following line is

included at the beginning of your program:

#include "windecl.h"

After you have written your C application program, you must compile your application

program using one of the following compilers: Microsoft C Version 7.0 with Microsoft

SDK (Software Development Kit) Version 3.1 or Microsoft Visual C++ Version 1.0 (also

known as Microsoft C Version 8.0). Then link your application with the C language

interface, gpib.lib. Use the following command to compile and link a QuickWin C

application named cprogusing Microsoft C:

cl /Mq cprog.c gpib.lib

The /Mq option of Microsoft C creates a QuickWin application. To run your application,

choose the Run option from the File menu in the Program Manager window. Enter the

path and name of the compiled program in the dialog box that pops up.

Borland C++

Before you compile your C application program, make sure that the following line is

included at the beginning of your program:

#include "windecl.h"

After you have written your C application program, you must compile your application

program using the Borland C++ (version 2.0 or higher) compiler. Then link your

application with the C language interface, gpib.lib. Use the following command to

compile and link a Windows C application named cprog using Borland C++:

bcc -W cprog.c gpib.lib

The -W option of Borland C++ creates a Windows application. To run your application,

choose the Run option from the File menu in the Program Manager window. Enter the

path and name of the compiled program in the dialog box that pops up.

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NI-488.2 User Manual for Windows

Developing Your Application

Chapter 3

Visual Basic

With Visual Basic, you access the NI-488 functions as subroutines, using the BASIC

keyword CALL followed by the NI-488 function name (for example CALL ibtrg

(ud%)). You can also access the NI-488 functions using another set of functions, the il

functions (for example result% = iltrg (ud%)). If you are using Visual Basic

and prefer calling functions instead of subroutines, then you can use the il functions.

With some of the ib commands (for example, ibrd) the length of the string buffer is

automatically calculated within the actual subroutine, which eliminates the need to pass

in the length as an extra parameter.

Before you run your Visual Basic application, include the files niglobal.basand

vbib.basin your application project file.

If you are using Microsoft Visual Basic 1.0, you must edit niglobal.bas to define

the constants trueand false as follows:

global const true = -1

global const false = 0

In Microsoft Visual Basic 2.0 and higher, true and false are reserved words;

therefore, these constants are no longer defined in niglobal.bas.

After you have written your Visual Basic application, choose the Start option from the

Run menu to execute your program.

Direct Entry with C

Before you compile your C application program, make sure that the following lines are

included at the beginning of your program:

#ifdef __cplusplus

extern "C"{

#endif

#include "windecl.h

int ibsta, iberr;

long ibcntl;

/* NI-488.2 global status variables */

#ifdef __cplusplus

}

#endif

You must define the global status variables in your application program.

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Developing Your Application

Sample programs using direct entry are included with the National Instruments driver.

The C sample programs are console-type applications. They illustrate how to use the

function calls the NI-488.2 driver exports. Since most of the popular compilers support

console-type applications as well as GUI applications, you can create console-type

applications without knowing Windows GUI programming. A console-type application

is a Win16 program that uses text-based input and output instead of a graphical interface.

This allows you to quickly create a Win16 application by using simple input and output

functions like printfand scanf.

You must define the direct entry prototypes of the functions used in your application

program. There are three methods of accessing the Dynamic Link Library (DLL)

directly. The NI-488.2 Function Reference Manual for DOS/Windows provides the

format for the first two methods. Refer to it for the C direct entry syntax for NI-488

functions and NI-488.2 routines. The direct entry sample programs use the third method.

The three methods of direct entry are documented in the Microsoft Windows Software

Development Kit (SDK) Guide's online help file. The first method of accessing the DLL

follows.

Method 1. List Functions in the Module Definition File

To use the first method, list the names of the functions in the importssection in the

application's .def file.

You must create a module definition file, such as cprog.def. This file contains an

imports section that lists the direct entry points used by the application program. You

must link the module definition file to your application program.

After you have written your Microsoft C application program, compile your program and

use the /Mq option of Microsoft C to create a QuickWin application. This option is

available starting with Microsoft C/C++ Version 7.0 with the Microsoft Software

Development Kit (SDK) or with Microsoft Visual C++ Version 1.x. The following

command compiles and links a Microsoft QuickWin application named cprog with the

module definition file cprog.def:

cl /Mq cprog.c cprog.def

After you have written your Borland C/C++ application program, compile your program

and use the -W option of Borland C/C++ to create a Windows application. The following

command compiles and links a Borland C/C++ Windows application named cprog with

the module definition file cprog.def:

bcc -W cprog.c cprog.def

To run your application, choose the Run option from the File menu in the

Program Manager window. Enter the path and name of the compiled program in the

dialog box that appears.

The second method of accessing the DLL follows.

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Developing Your Application

Chapter 3

Method 2. Generate an Import Library Using implib

To use the second method, link the application to an import library generated from the

DLL using the implibutility.

To generate the import library, type in the following text:

implib gpib.lib c:\windows\system\gpib.dll

where c:\windows\system\is the path to your Windows System directory. The file

named gpib.libis the name of the file generated by the implibutility. For more

information about the implibutility program, refer to the Windows online help or other

documentation supplied with your compiler.

After you have written your Microsoft C application program, compile your program and

use the /Mq option of Microsoft C to create a QuickWin application. This option is

available starting with Microsoft C/C++ Version 7.0 with the Microsoft Software

Development Kit (SDK) or with Microsoft Visual C++ Version 1.x. The following

command compiles and links a Microsoft QuickWin application named cprog with the

import library file gpib.lib:

cl /Mq cprog.c gpib.lib

After you have written your Borland C/C++ application program, compile your program

and use the -W option of Borland C/C++ to create a Windows application. The following

command compiles and links a Borland C/C++ Windows application named cprog with

the import library file gpib.lib:

bcc -W cprog.c gpib.lib

To run your application, choose the Run option from the File menu in the

Program Manager window. Enter the path and name of the compiled program in the

dialog box that appears.

The third method of accessing the DLL follows.

Method 3. Use LoadLibrary and GetProcAddress

To use the third method, use the LoadLibraryand GetProcAddressfunctions to

load the library and retrieve a pointer to the function.

The Direct Entry sample programs use this method. At the beginning of your program,

declare the following global variable for the DLL as follows:

HINSTANCE GpibLib = NULL;

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The prototypes for each function can be found in the NI-488.2 Function Reference

Manual for DOS/Windows. For functions that return an integer value, like ibdev, you

must cast the pointer to the function as follows:

int(_far _pascal *Pname)

where *Pname is the name of the pointer to the function. For functions (that is, the

NI-488.2 calls) that do not return a value, you must cast the pointer to the function as

follows:

void(_far _pascal *Pname)

where *Pname is the name of the pointer to the function. A function is followed by its

list of parameters and pointers to the three global variables, as described in the NI-488.2

Function Reference Manual for DOS/Windows. The following is an example of how to

cast the function pointer and how to set up the parameter list for ibdev and ibonl:

int(_far _pascal *Pibdev)(int BdIndx, int pad, int sad,

int tmo, int eot, int eos, int _far *ibsta,

int _far *iberr, long _far *ibcntl);

int(_far _pascal *Pibonl)(int ud, int v, int _far *ibsta,

int _far *iberr, long _far *ibcntl);

You must load the GPIB.DLLlibrary within your application program. The following

code calls the LoadLibraryfunction and handles errors:

GpibLib=LoadLibrary("GPIB.DLL");

if (GpibLib <= HINSTANCE_ERROR)

{

return FALSE;

}

Next you must get the address and assign it to the function pointer by using the

GetProcAddressfunction. This code goes in your application program.

Pibdev=(int (_far _pascal *)(int, int, int, int, int, int,

int _far*, int _far *, long _far *))

GetProcAddress(GpibLib,(LPCSTR)"DLLibdev");

Pibonl=(int (_far _pascal *)(int, int, int _far *, int _far *,

long _far *))GetProcAddress(GpibLib,

(LPCSTR)"DLLibonl");

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NI-488.2 User Manual for Windows

Developing Your Application

Chapter 3

If GetProcAddressdoes not return a pointer, you can check to see if an address was

assigned or not, as in the following example:

if ((Pibdev==NULL)||

(Pibonl==NULL))

{

FreeLibrary(GpibLib);

GpibLib=NULL;

return FALSE;

}

else

return TRUE;

The following code shows you how to call functions from within your application

program:

dvm = (*Pibdev) (0, 1, 0, T10s, 1, 0, &ibsta, &iberr,

&ibcntl);

(*Pibonl) (dvm, 0, &ibsta, &iberr, &ibcntl);

Upon completion of your program, you must free the library, as in the following

example:

FreeLibrary(GpibLib);

For more information about the Windows functions like LoadLibraryand

GetProcAddress, refer to the Windows SDK documentation or your compiler's

Windows documentation.

After you have written your Microsoft C application program, compile your program and

use the /Mq option of Microsoft C to create a QuickWin application. This option is

available starting with Microsoft C/C++ Version 7.0 with the Microsoft Software

Development Kit (SDK) or with Microsoft Visual C++ Version 1.x. The following

command compiles and links a Microsoft QuickWin application named cprog:

cl /Mq cprog.c

After you have written your Borland C/C++ application program, compile your program

and use the -W option of Borland C/C++ to create a Windows application. The following

command compiles and links a Borland C/C++ Windows application named cprog:

bcc -W cprog.c

To run your application, choose the Run option from the File menu in the Program

Manager window. Enter the path and name of the compiled program in the dialog box

that appears.

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Direct Entry with Visual Basic

See the Visual Basic section, earlier in this chapter, for information on calling the NI-488

functions with Visual Basic.

Include the file niglobal.basin your application project file. You must create a file

(for example, dllfunc.bas) that contains the direct entry prototypes of the functions

used in your application program. Include the direct entry file in your application project

file. Refer to the NI-488.2 Function Reference Manual for DOS/Windows for the Visual

Basic direct entry syntax for NI-488 and NI-488.2 functions.

If you are using Microsoft Visual Basic 1.0, you must edit niglobal.basto define the

constants true and false as follows:

global const true = -1

global const false = 0

In Microsoft Visual Basic 2.0 and higher, true and false are reserved words;

therefore, these constants are no longer defined in niglobal.bas.

After you have written your Visual Basic application, choose the Start option from the

Run menu to execute your program.

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NI-488.2 User Manual for Windows

Chapter 4

Debugging Your Application

This chapter describes several ways to debug your application program.

Running wibtest

Before you run your application program, you should run the software diagnostic test,

wibtest, that came with your NI-488.2 software. The wibtestprogram is an

NI-488.2 application that makes calls to the driver. If wibtest passes, your GPIB

hardware and NI-488.2 software are interacting correctly. The following paragraphs

describe the messages you might receive while running wibtest, and how to resolve

each problem. The term gpibx refers to one of the boards gpib0, gpib1, gpib2, and

gpib3.

Presence Test of Driver

The wibtestprogram tests for the presence of the NI-488.2 driver gpib.dlland the

NI-488.2 configuration information file gpib.ini. If gpib.dllis not in the

Windows directory, a warning box pops up with the following text:

File Error: Cannot find GPIB.DLL

Press the Close button. wibtest displays the following error message when it fails:

<<< No driver present for GPIBx. >>>

To correct the problem, make sure that the file gpib.dllis in the Windows directory

(usually c:\windows). The same error message is displayed if gpib.iniis not

located in the Windows directory. If you are unable to locate gpib.dllor gpib.ini,

you should reinstall the NI-488.2 software.

Presence Test of Board

The following error message appears if the board gpibxis not installed or if the

software is not configured properly:

<<< No board present for GPIBx. >>>

If this message appears, you could have one of the following situations:

•

The Use this GPIB Interfacefield in wibconf might be set to no for

board gpibx. If you want to use the board, you must set this field to yes.

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Debugging Your Application

Chapter 4

•

The board might not be properly installed and configured. Refer to the getting

started manual for detailed instructions.

The software and hardware settings do not match. You can run wibconfto check

the current configuration of the software.

GPIB Cables Connected

The following error message appears if a GPIB cable is connected to the board when you

run wibtest:

Call(25) 'ibcmd " "' failed, ibsta (0x134) not what was expected

(0x8130)

Call(25) 'ibcmd " "' failed, expected ibsta (0x100) to have the

ERR bit set.

Disconnect all GPIB cables before trying the test again.

Running GPIBInfo

The GPIBInfo utility program is a simple diagnostic tool you can use to obtain

information about the NI-488.2 software you are using and any GPIB interface boards in

your system. This information helps you determine the capabilities of your NI-488.2

software and is also helpful if you need to call National Instruments for technical support.

If you run GPIBInfowith no specific parameters, the program displays software

information such as the name and version of your GPIB software, the type of GPIB

interface board and functions that you can use with the software, and whether or not you

can use the HS488 high-speed protocol. GPIBInfoalso displays information about

each GPIB interface board installed in your system, including the name of the board, its

Controller chip, the hardware settings, the type of functions that the board can use, and

whether or not the board can use the HS488 high-speed communication protocol. The

typical GPIBInfo output is as follows:

GPIBInfo (Sep 29 1993)

reserved.

Software Information:

The NI-488.2 Software for Windows 3 is loaded.

You are running Version 2.5 for the AT-GPIB/TNT board.

It supports both the NI-488 functions and the NI-488.2 routines.

It supports the HS488 high-speed protocol.

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Hardware Information:

GPIB0:an AT-GPIB/TNT board using the TNT4882C chip.

It supports both the NI-488 functions and NI-488.2

routines.

It supports the HS488 high-speed protocol.

It uses base I/O address 0x2C0.

It uses interrupt level 11.

It uses DMA channel 5.

You can also run GPIBInfo by specifying the base I/O address of a GPIB board in your

system. If GPIBInfofinds a board at the given address, it displays information about

that board. This feature of GPIBInfois useful in determining whether you have a

GPIB board installed at a particular address. If you have a board installed at base I/O

address 2C0 (hex), entering gpibinfo 0x2c0produces the following output:

GPIBInfo (Sep 29 1993)

reserved.

The board at base I/O address 0x2C0 appears to be an AT-GPIB/TNT.

It uses the TNT4882C GPIB Controller chip.

It supports both the NI-488 functions and the NI-488.2 routines.

It supports the HS488 high-speed protocol.

The NI-488.2 software is configured to access this board as

GPIB0.

Debugging with the Global Status Variables

After each function call to your NI-488.2 driver, ibsta, iberr, ibcnt, and ibcntl

are updated before the call returns to your application. You should check for an error

after each GPIB call. Refer to Chapter 3, Developing Your Application, for more

information about how to use these variables within your program to automatically check

for errors.

After you determine which GPIB call is failing and note the corresponding values of the

global variables, refer to Appendix A, Status Word Conditions, and Appendix B, Error

Codes and Solutions. These appendixes will help you interpret the state of the driver.

4-3

NI-488.2 User Manual for Windows

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Debugging Your Application

Chapter 4

Debugging with wibic

If your application does not automatically check for and display errors, you can locate an

error by using wibic. Simply issue the same functions or routines, one at a time as they

appear in your application program. Because wibicreturns the status values and error

codes after each call, you should be able to determine which GPIB call is failing. For

more information about wibic, refer to Chapter 5, wibic–Windows Interface Bus

Interactive Control Utility.

After you determine which GPIB call is failing and note the corresponding values of the

global variables, refer to Appendix A, Status Word Conditions, and Appendix B, Error

Codes and Solutions. These appendixes will help you interpret the state of the driver.

Debugging with GPIB Spy

The NI-488.2 software includes GPIB Spy, an applications monitor utility that is useful

as a debugging tool. You can use GPIB Spy to monitor the NI-488 and NI-488.2 calls

made by your Windows application. You can configure GPIB Spy to suspend the

execution of your application and display an information screen any time the error bit is

set in ibsta. For more information about GPIB Spy, refer to Chapter 6, GPIB Spy.

GPIB Error Codes

Table 4-1 lists the GPIB error codes. Remember that the error variable is meaningful

only when the ERR bit in the status variable is set. For a detailed description of each

error and possible solutions, refer to Appendix B, Error Codes and Solutions.

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Debugging Your Application

Table 4-1. GPIB Error Codes

Error

iberr

Value

Mnemonic

EDVR

ECIC

Meaning

Windows error

Function requires GPIB board to be CIC

No Listeners on the GPIB

GPIB board not addressed correctly

Invalid argument to function call

GPIB board not System Controller as required

I/O operation aborted (timeout)

Nonexistent GPIB board

ENOL

EADR

EARG

ESAC

EABO

ENEB

EDMA

EOIP

DMA error

Asynchronous I/O in progress

No capability for operation

File system error

ECAP

EFSO

EBUS

ESTB

GPIB bus error

Serial poll status byte queue overflow

SRQ stuck in ON position

Table problem

ESRQ

ETAB

Configuration Errors

Several applications require customized configuration of the GPIB driver. For example,

you might want to terminate reads on a special end-of-string character, or you might

require secondary addressing. In these cases, you can use either the wibconf utility to

permanently reconfigure the driver, or you can programmatically modify the driver while

your application is running by using the NI-488 ibconfigfunction.

Note: To change settings other than base I/O address, interrupt level, or DMA

channel, National Instruments recommends using ibconfiginstead of

running the wibconfutility.

If your application uses ibconfig, it will always work regardless of the previous

configuration of the driver. Refer to the description of ibconfigin the NI-488.2

Function Reference Manual for DOS/Windows for more information.

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Debugging Your Application

Chapter 4

To test the configuration of your hardware, you can use the ibdiagprogram as

described in your getting started manual.

Timing Errors

If your application fails, but the same calls issued in wibic are successful, your program

might be issuing the NI-488.2 calls too quickly for your device to process and respond to

them. This problem can also result in corrupted or incomplete data.

A well behaved IEEE 488 device should hold off handshaking and set the appropriate

transfer rate. If your device is not well behaved, you can test for and resolve the timing

error by single-stepping through your program and inserting finite delays between each

GPIB call. One way to do this is to have your device communicate its status whenever

possible. Although this method is not possible with many devices, it is usually the best

option. Your delays will be controlled by the device and your application can adjust

itself and work independently on any platform. Other delay mechanisms will probably

cause varying delay times on different platforms.

Communication Errors

Repeat Addressing

Some devices require GPIB addressing before any GPIB activity. Devices adhering to

the IEEE 488.2 standard should remain in their current state until specific commands are

sent across the GPIB to change their state. You might need to configure your NI-488.2

driver to perform repeat addressing if your device does not remain in its currently

addressed state. Refer to Chapter 8, wibconf–Windows Interface Bus Configuration

Utility, or to the description of ibconfig(option IbcREADDR) in the NI-488.2

Function Reference Manual for DOS/Windows for more information about reconfiguring

your software.

Termination Method

You should be aware of the data termination method that your device uses. By default,

your NI-488.2 software is configured to send EOI on writes and terminate reads on EOI

or a specific byte count. If you send a command string to your device and it does not

respond, it might be because it does not recognize the end of the command. You might

need to send a termination message such as <CR> <LF> after a write command as

follows:

ibwrt(dev,”COMMAND\x0A\x0D”,9);

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Chapter 4

Debugging Your Application

Common Questions

Can I have the DOS and Windows drivers installed at the same time?

Yes, there is nothing wrong with installing both. However, it is better not to access them

at the same time.

What do I do if ibdiag or wibtest fail with an error?

Refer to the Running wibtest section of this chapter and to the section about ibdiagin

your getting started manual for specific information about what might cause these tests to

fail.

How do I communicate with my instrument over the GPIB?

Refer to the documentation that came from the instrument manufacturer. The command

sequences you use are totally dependent on the specific instrument. The documentation

for each instrument should include the GPIB commands you need to communicate with

it. In most cases, NI-488 device-level calls are sufficient for communicating with

instruments. Refer to Chapter 3, Developing Your Application, for more information.

Can I use the NI-488 and NI-488.2 calls together in the same application?

Yes, you can mix NI-488 functions and NI-488.2 routines.

What can I do to check for errors in my GPIB application?

Examine the value of ibsta after each NI-488 or NI-488.2 call. If a call fails, the ERR

bit of ibsta is set and an error code is stored in ibcntl. For more information about

global status variables, refer to Chapter 3, Developing Your Application.

How do I use wibic?

You can use wibicto practice communication with your instrument, troubleshoot

problems, and develop your application program. For instructions, refer to Chapter 5,

wibic–Windows Interface Bus Interactive Control Utility.

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Debugging Your Application

Chapter 4

What should I type into the pop-up window that appears when I start wibconf?

This pop-up window is prompting you for the drive and path where the gpib.inifile is

located. If Windows is installed in the default directory (c:\windows), just press

<Return>. If Windows is not installed in the default directory, enter the path and

directory where Windows is installed so that wibconf can find the correct gpib.ini

file to modify, for example c:\win31\gpib.ini.

How can I determine which type of GPIB board I have installed?

Run the GPIBInfoutility. If you run GPIBInfowithout specifying any parameters, it

returns information about the GPIB boards currently configured for use in your system.

If you know the base I/O address of a GPIB interface board, you can enter it as a

parameter for specific information. For example, gpibinfo 2C0returns information

about the GPIB board at base I/O address 2C0.

How can I determine which version of the NI-488.2 software I have installed?

Run the GPIBInfoutility. If you run GPIBInfowithout specifying any parameters, it

provides information about the version of the NI-488.2 software currently installed.

Why can't I launch Windows after installing Windows 3.1 on top of my

Windows 3.0 installation?

If the system.ini file contains conflicting information about which virtual devices to

load, Windows fails to start. In this case, the system.inifile is probably trying to

load two virtual DMA devices. The system.inifile should include the lines to load

only one virtual DMA device. You can either delete unwanted lines or change them to

comment lines by adding a semicolon at the beginning of the line.

The virtual DMA device is loaded in the [386Enh] section of the system.inifile.

The correct one to use with Windows 3.1 is loaded by the following line:

device=*vdmad

The correct one to use with Windows 3.0 is loaded by the following line:

device=drive:\path\nivdmad.386

where drive and path describe the location of the nivdmad.386file on your hard

disk (for example c:\at-gpibw).

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Chapter 4

Debugging Your Application

What information should I have before I call National Instruments?

When you call National Instruments, you should have the results of the diagnostic tests

ibdiag and wibtest along with the output from the GPIBInfoutility. Also, make

sure you have filled out the technical support form in Appendix C, Customer

Communication.

4-9

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Chapter 5

wibic–Windows Interface Bus Interactive

Control Utility

This chapter introduces you to wibic, the interactive control program that you can use

to communicate with GPIB devices interactively.

Overview

With the wibicprogram, you communicate with the GPIB devices through functions

you enter at the keyboard. For specific information about how to communicate with your

particular device, refer to the manual that came with the device. You can use wibic to

practice communicating with the instrument, troubleshoot problems, and develop your

application program.

One way wibic helps you to learn about your instrument and to troubleshoot problems

is by displaying the following information on your screen whenever you enter a

command:

•

The results of the status word (ibsta) in hexadecimal notation

The mnemonic constant of each bit set in ibsta

The mnemonic value of the error variable (iberr) if an error exists (the ERR bit is

set in ibsta)

•

The count value for each read, write, or command function

The data received from your instrument

Example Using NI-488 Functions

This section shows how you might use wibicto test a sequence of NI-488 device

function calls. You do not need to remember the parameters that each function takes. If

you enter the function name only, wibicprompts you for the necessary parameters.

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

1. To run wibic, double-click on the wibic icon in the GPIB group in the Program

Manager. A window appears with the following information displayed:

National Instruments

IEEE 488 Interface Bus Interactive Control Program (WIBIC)

Version Date: May 28 1993 Version Time: 09:42:25

Type 'help' for help or 'q' to quit

2. Use ibdev to find the device name which is assigned to your device in the

wibconfprogram. The following example shows how you could use ibdev to

open a device, assign it to access board gpib0, choose a primary address of 6 with

no secondary address, set a timeout of 10 s, enable the END message, and disable the

EOS mode:

:ibdev

enter board index: 0

enter primary address: 6

enter secondary address: 0

enter timeout: 13

enter 'EOI on last byte' flag: 1

enter end-of-string mode/byte: 0

id = 32256

ud0:

You could also input all the same information with the ibdevcommand as follows:

:ibdev 0 6 0 13 1 0

id = 32256

ud0:

3. Clear the device as follows:

ud0: ibclr

[0100] (cmpl)

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wibic–Windows Interface Bus Interactive Control Utility

4. Write the function, range, and trigger source instructions to your device. Refer to the

instrument's user manual for the command bytes that work with your instrument.

ud0: ibwrt

enter string: "*RST; VAC; AUTO; TRIGGER 2; *SRE 16"

[0100] (cmpl)

ud0: ibwrt "*RST; VAC; AUTO; TRIGGER 2; *SRE 16"

[0100] (cmpl)

5. Trigger the device as follows:

ud0: ibtrg

[0100] (cmpl)

6. Wait for a timeout or for your device to request service. If the current timeout limit

is too short, use ibtmoto change it. Use the ibwaitcommand as follows:

ud0: ibwait

enter wait mask: TIMO RQS

[0900] (rqs cmpl)

ud0: ibwait TIMO RQS

[0900] (rqs cmpl)

7. Read the serial poll status byte. This serial poll status byte varies depending on the

device used.

ud0: ibrsp

[0100] (cmpl)

Poll: 0x40 (decimal : 64)

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

8. Use the read command to display the data on the screen both in hex values and their

ASCII equivalents.

ud0: ibrd

enter byte count: 18

[0100] (cmpl)

4e 44 43 56 20 30 30 30

2e 30 30 34 37 45 2b 30

0a 0a

N D C V 0 0 0

. 0 0 4 7 E + 0

. .

ud0: ibrd 18

[0100] (cmpl)

4e 44 43 56 20 30 30 30

2e 30 30 34 37 45 2b 30

0a 0a

N D C V 0 0 0

. 0 0 4 7 E + 0

. .

9. Place the device offline as follows:

ud0: ibonl

enter value: 0

[0100] (cmpl)

ud0: ibonl 0

[0100] (cmpl)

10. Terminate the wibicprogram by entering qat the prompt.

wibic Syntax

When you enter commands in wibic, you can either include the parameters, or the

program prompts you for values. Some commands require numbers as input values.

Others might require you to input a string.

Number Syntax

You can enter numbers as hexadecimal, octal, or decimal integer.

Hexadecimal numbers–You must precede hex numbers by zero and x (for example, 0xD).

Octal numbers–You must precede octal numbers by zero only (for example, 015).

Decimal numbers–Enter the number only.

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wibic–Windows Interface Bus Interactive Control Utility

String Syntax

You can enter strings in the following formats.

ASCII character sequence–You must enclose the entire sequence in quotation marks.

Octal bytes–You must use a backslash character followed by the octal value. For

example, octal 40 is represented by \40.

Hex bytes–You must use a backslash character and an xfollowed by the hex value. For

example, hex 40 is represented by \x40.

Special Symbols–Some instruments require special termination or end-of-string (EOS)

characters that indicate to the device that a transmission has ended. The two most

common EOS characters are \r and \n. \r represents a carriage return character and

\n represents a linefeed character. You can use these special characters to insert the

carriage return and linefeed characters into a string, as in "F3R5T1\r\n".

Address Syntax

Many of the NI-488.2 routines have an address or address list parameter. An address is a

16-bit representation of the GPIB address of a device. The primary address is stored in

the low byte and the secondary address, if any, is stored in the high byte. For example, a

device at primary address 6 and secondary address 0x67 has an address of 0x6706. A

NULL address is represented as 0xffff.

wibic Syntax for NI-488 Functions

Table 5-1 and Table 5-2 summarize the syntax of NI-488 functions in wibic.

vrepresents a number that you input. string represents a string that you input. For

more information about the function parameters, use the wibichelp feature or refer to

the NI-488.2 Function Reference Manual for DOS/Windows.

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

Table 5-1. Syntax for Device-Level NI-488 Functions in wibic

Syntax

Description

ibask mn

Return configuration information where mn is a mnemonic for a

configuration parameter or equivalent integer value

ibbna brdname

Change access board of device where brdname is symbolic

name of new board

ibclr

Clear specified device

ibconfig mn v

Alter configurable parameters where mnis mnemonic for a

configuration parameter or equivalent integer value

ibdev vvvvvv

Open an unused device

ibdev parameters are board id, pad, sad, tmo, eos, eot

ibeos v

ibeot v

ibln v v

ibloc

Change/disable EOS message

Enable/disable END message

Check for presence of device on the GPIB at pad, sad

Go to local

ibonl v

ibpad v

ibpct

Place device online or offline

Change primary address

Pass control

ibppc v

ibrd v

Parallel poll configure

Read data where vis the bytes to read

Read data asynchronously where vis the bytes to read

Read data to file where flnameis pathname of file to read

Conduct a parallel poll

ibrda v

ibrdf flname

ibrpp

ibrsp

Return serial poll byte

ibsad v

ibstop

Change secondary address

Abort asynchronous operation

Change/disable time limit

ibtmo v

ibtrg

Trigger selected device

ibwait mask

Wait for selected event where mask is a hex, octal, or decimal

integer or a mask bit mnemonic

ibwrt string

ibwrta string

ibwrtf flname

Write data

Write data asynchronously

Write data from a file where flnameis pathname of file to write

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wibic–Windows Interface Bus Interactive Control Utility

Table 5-2. Syntax for Board-Level NI-488 Functions in wibic

Syntax

Description

ibask mn

Return configuration information where mn is a mnemonic for a

configuration parameter or equivalent integer value

ibcac v

Become Active Controller

ibcmd string

ibcmda string

ibconfig mn v

Send commands

Send commands asynchronously

Alter configurable parameters where mnis mnemonic for a

configuration parameter or equivalent integer value

ibdma v

Enable/disable DMA

ibeos v

Change/disable EOS message

Enable/disable END message

Return the oldest recorded event

ibeot v

ibevent

ibfind udname

Return unit descriptor where udnameis the symbolic name of a

board (for example, or gpib0)

ibgts v

ibist v

iblines

ibln v v

ibloc

Go from Active Controller to standby

Set/clear ist

Read the state of all GPIB control lines

Check for presence of device on the GPIB at pad, sad

Go to local

ibonl v

ibpad v

ibppc v

ibrd v

Place device online or offline

Change primary address

Parallel poll configure

Read data where vis the bytes to read

Read data asynchronously where vis the bytes to read

Read data to file where flnameis pathname of file to read

Conduct a parallel poll

ibrda v

ibrdf flname

ibrpp

ibrsc v

ibrsv v

ibsad v

ibsic

Request/release system control

Request service

Change secondary address

Send interface clear

ibsre v

ibstop

Set/clear remote enable line

Abort asynchronous operation

Change/disable time limit

ibtmo v

ibwait mask

Wait for selected event where mask is a hex, octal, or decimal

integer or a mask bit mnemonic

ibwrt string

ibwrta string

ibwrtf flname

Write data

Write data asynchronously

Write data from a file where flnameis pathname of file to write

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

wibic Syntax for NI-488.2 Routines

Table 5-3 summarizes the syntax of NI-488.2 routines in wibic. vrepresents a number

and string represents a string. address represents an address, and addrlist

represents a list of addresses separated by commas. For more information about the

routine parameters, use the wibichelp feature or refer to the NI-488.2 Function

Reference Manual for DOS/Windows.

Table 5-3. Syntax for NI-488.2 Routines in wibic

Description

Routine Syntax

AllSpoll addrlist

Serial poll multiple devices

Clear a device

DevClear address

DevClearList addrlist

EnableLocal addrlist

EnableRemote addrlist

FindLstn padlist v

FindRQS addrlist

PassControl address

PPoll

Clear multiple devices

Enable local control

Enable remote control

Find all Listeners

Find device asserting SRQ

Pass control to a device

Parallel poll devices

PPollConfig address v v

PPollUnconfig addrlist

RcvRespMsg v v

Configure device for parallel poll

Unconfigure device for parallel poll

Receive response message

Serial poll a device

ReadStatusByte address

Receive address v v

ReceiveSetup address

ResetSys addrlist

Send address string v

SendCmds string

Receive data from a device

Receive setup

Reset multiple devices

Send data to a device

Send command bytes

Send data bytes

SendDataBytes bufferv

SendIFC

Send interface clear

SendList addrlist string v

SendLLO

Send data to multiple devices

Put devices in local lockout

Send setup

SendSetup addrlist

Set 488.2 v

Enter 488.2 mode for board v

(continues)

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wibic–Windows Interface Bus Interactive Control Utility

Table 5-3. Syntax for NI-488.2 Routines in wibic (Continued)

Description

Routine Syntax

SetRWLS addrlist

TestSys addrlist

TestSRQ

Put devices in remote with lockout state

Causes multiple devices to perform self tests

Test for service request

Trigger address

TriggerList addrlist

WaitSRQ

Trigger a device

Trigger multiple devices

Wait for service request

Status Word

In wibic, all NI-488 functions (except ibfindand ibdev) and NI-488.2 routines

return the status word ibstain two forms: a hex value in square brackets and a list of

mnemonics in parentheses. In the following example, the status word is on the second

line. It shows that the device function write operation completed successfully:

ud0: ibwrt "f2t3x"

[0100] (cmpl)

ud0:

For more information about the status word, refer to Chapter 3, Developing Your

Application.

Error Information

If an NI-488 function or NI-488.2 routine completes with an error, wibicdisplays the

relevant error mnemonic. In the following example, the error condition EBUS has

occurred during a data transfer.

ud0: ibwrt "f2t3x"

[8100] (err cmpl)

error: EBUS

ud0:

In this example, the addressing command bytes could not be transmitted to the device.

This indicates that either dev1is powered off, or the GPIB cable is disconnected.

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Chapter 5

For a detailed list of the error codes and their meanings, refer to Chapter 4, Debugging

Your Application.

Count

When an I/O function completes, wibic displays the actual number of bytes sent or

received, regardless of the existence of an error condition.

If one of the addresses in an address list of an NI-488.2 routine is invalid, then the error is

EARG and wibic displays the index of the invalid address as the count.

The count has a different meaning depending on which NI-488 function or NI-488.2

routine is called. Refer to the function descriptions in the NI-488.2 Function Reference

Manual for DOS/Windows for the correct interpretation of the count return.

Common NI-488 Functions

ibfind

Use the ibfind function to open a board. The following example opens gpib0.

:ibfind gpib0

id = 32000

gpib0:

id is the unit descriptor of the board. The prompt gpib0indicates that the board is

open.

Any name you use with the ibfindfunction must be a valid symbolic name in the

driver. gpib0 is the default name found in the driver. For more information about valid

names, refer to Chapter 8, wibconf–Windows Interface Bus Configuration Utility.

ibdev

The ibdev command initializes a device descriptor with the input information.

With ibdev, you specify the following values:

•

Access board for the device

Primary address

•

Secondary address

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wibic–Windows Interface Bus Interactive Control Utility

•

Timeout setting

EOT mode

•

EOS mode

The following example shows ibdevopening an available device and assigning it to

access gpib0( board = 0) with a primary address of 6 (pad = 6), a secondary address

of hex 67 (sad = 0x67), a timeout of 10 s (tmo=13), the END message enabled

(eot =1), and the EOS mode disabled (eos= 0).

:ibdev 0 6 0x67 13 1 0

id = 32256

ud0:

If you use ibdev without specifying parameters, wibic prompts you for the input

parameters as shown in the following example:

:ibdev

enter board index: 0

enter primary address: 6

enter secondary address: 0x67

enter timeout: 13

enter ‘EOI on last byte’ flag: 1

enter end-of-string mode/byte: 0

id = 32256

ud0:

Three distinct errors can occur with the ibdev call:

•

EDVR–No device is available, the board index entered refers to a nonexistent board

(that is, not 0, 1, 2, or 3) or Windows cannot locate the gpib.dllfile and/or

gpib.ini file. The following example illustrates an EDVR error.

:ibdev 4 6 0x67 7 1 0

id = -1

[8000] (err)

error: EDVR (2)

•

ENEB–The board index entered refers to a known board (such as 0), but the driver

cannot find the board. In this case, run wibconf to verify that the base address of

the board is set correctly and that the Use This GPIB Interfacefield is set to

yes.

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

•

EARG–One of the last five parameters is an invalid value. The ibdevcall returns

with a new prompt and the EARG error (invalid function argument). If the ibdev

call returns with an EARG error, you must identify which parameter is incorrect and

use the appropriate command to correct it. In the following example, pad has an

invalid value. You can correct it with an ibpadcall as shown:

:ibdev 0 66 0x67 7 1 0

id = 32256

[8100] (err cmpl)

error: EARG

ud0: ibpad 6

previous value: 16

ibwrt

The ibwrt command sends data from one GPIB device to another. For example, to

send the six character data string F3R5T1from the computer to a device, you enter the

following string at the prompt as shown in the following example:

ud0: ibwrt "F3R5T1"

[0100] (cmpl)

The returned status word contains the cmpl bit, which indicates a successful I/O

completion. The byte count 6indicates that all six characters were sent from the

computer and received by the device.

ibrd

The ibrd command causes a GPIB device to receive data from another GPIB device.

The following example acquires data from the device and displays it on the screen in hex

format and in its ASCII equivalent, along with the status word and byte count.

ud0: ibrd 20

[2100] (end cmpl)

4e 44 43 56 28 30 30 30

2e 30 30 34 37 45 2b 30

0d 0a

N D C V 9 0 0 0

. 0 0 4 7 E + 0

. .

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wibic–Windows Interface Bus Interactive Control Utility

Common NI-488.2 Routines in wibic

Set

You must use the setcommand before you can use NI-488.2 routines in wibic. The

syntax for this form of the setcommand is as follows:

set 488.2 n

where nrepresents a board number (for example, n=0 for gpib0).

The 488.2 prompt indicates that you are in NI-488.2 mode on board n. The following

example shows how to enter into 488.2 mode on board gpib0.

set 488.2 0

488.2 (0):

Send and SendList

The Send routine sends data to a single GPIB device. You can use the SendList

command to send data to multiple GPIB devices. For example, suppose you want to send

the five character string *IDN?followed by the new line character with EOI. You want

to send the message from the computer to the devices at primary address 2 and 17. To do

this, enter the SendListcommand at the 488.2 (0) prompt as shown in the

following example:

488.2 (0): SendList 2, 17 “*IDN?” NLend

[0128] (cmpl cic tacs)

The returned status word contains the cmpl bit, which indicates a successful I/O

completion. The byte count 6indicates that six characters, including the added new line,

were sent from the computer and received by both devices.

Receive

The Receiveroutine causes the GPIB board to receive data from another GPIB device.

The following example acquires 10 data bytes from the device at primary address 5. It

stops receiving data when 10 characters have been received or when the END message is

received. The acquired data is then displayed in hex format along with its ASCII

equivalent. The wibicprogram also displays the status word and the count of

transferred bytes.

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

488.2 (0): Receive 5 10 STOPend

[2124] (end cmpl cic lacs)

48 65 6c 6c 6f

Hello

Auxiliary Functions

Table 5-4 summarizes the auxiliary functions that you can use in wibic.

Table 5-4. Auxiliary Functions in wibic

Function

Description

set udname

Select active device or board where udname is the symbolic

name of the new device or board (for example, dev1 or gpib0).

Call ibfindor ibdev initially to open each device or board.

help [option]

Display help information where option is any NI-488 or

NI-488.2 call. If you do not enter an option, a menu of options

appears.

Repeat previous function.

Turn display off.

Turn display on.

n* function

Execute function ntimes where functionrepresents the

correct wibic function syntax.

n* !

Execute previous function ntimes.

$ filename

Execute indirect file where filenameis the pathname of a file

that contains wibicfunctions to be executed.

print string

buffer option

Display string on screen where stringis an ASCII character

sequence, octal bytes, hex bytes, or special symbols.

Set the type of display used for buffers. Valid options are full,

brief, ascii, and off. The default is full.

Exit or quit.

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wibic–Windows Interface Bus Interactive Control Utility

Set (Select Device or Board)

You can use the set command to select 488.2 mode or to communicate with a different

device. The following example switches communication from using NI-488.2 routines

for gpib0 to using a unit descriptor (ud0) previously acquired by an ibdev call.

488.2 (0): set ud0

ud0:

Help (Display Help Information)

The help feature displays a menu of topics to choose from. Each topic lists relevant

functions and other information. You can access help for a specific NI-488 function or

NI-488.2 routine by typing helpfollowed by the call name (for example, help

ibwrt). Help describes the function syntax for all NI-488 functions and NI-488.2

routines.

! (Repeat Previous Function)

The !function repeats the most recent function executed. The following example issues

an ibsic command and then repeats that same command.

gpib0: ibsic

[0130] (cmpl cic atn)

gpib0: !

[0130] (cmpl cic atn)

- (Turn Display Off) and + (Turn Display On)

The -function turns off all screen output except for the prompt. This function is useful

when you want to repeat any I/O function quickly without waiting for screen output to be

displayed.

The +function turns the screen output on.

In the following example 24 consecutive letters of the alphabet are read from a device

using three ibrd calls.

ud0: ibrd 8

[2100] (end cmpl)

61 62 63 64 65 66 67 68

a b c d e f g h

ud0: -

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wibic–Windows Interface Bus Interactive Control Utility

Chapter 5

ud0: ibrd 8

ud0: +

ud0: ibrd 8

[2100] (end cmpl)

71 72 73 74 75 76 77 78

q r s t u v w x

n* (Repeat Function n Times)

The n* function repeats the execution of the specified function ntimes, where nis an

integer. In the following example, the message Hellois sent five times to the device

described by ud0.

ud0: 5*ibwrt "Hello"

In the following example, the word Hello is sent five times, 20 times, and then 10 more

times.

ud0: 5*ibwrt "Hello"

ud0: 20* !

ud0: 10* !

Notice that the multiplier (*) does not become part of the function name; that is, ibwrt

"Hello"is repeated 20 times, not 5* ibwrt "Hello".

$ (Execute Indirect File)

The $function reads a specified file and executes the wibic functions listed in that file,

in sequence, as if they were entered in that order from the keyboard. The following

example executes the wibicfunctions listed in the file userfile.

gpib0: $ userfile

The following example repeats the operation three times.

gpib0: 3*$ userfile

The display mode that is in effect before this function was executed can be changed by

functions in the indirect file.

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wibic–Windows Interface Bus Interactive Control Utility

Print (Display the ASCII String)

You can use the print function to echo a string to the screen. The following example

shows how you can use ASCII or hex with the print command.

dev1: print "hello"

hello

dev1: print "and\r\n\x67\x6f\x6f\x64\x62\x79\x65"

and

goodbye

You can also use print to display comments from indirect files. The print string

appears even if the display is suppressed with the -function.

Buffer (Set Buffer Display Mode)

You can set the type of display used for buffers to control how much of the buffer is

displayed. full displays the entire buffer, briefdisplays the first and last eight bytes

of the buffer, ascii displays the entire buffer in ASCII mode, and off displays none of

the buffer.

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NI-488.2 User Manual for Windows

Chapter 6

GPIB Spy

This chapter explains how to use the GPIB Spy utility to monitor and debug your

application program.

Overview

GPIB Spy is a GPIB application monitor utility for Windows applications. It monitors

the NI-488 and NI-488.2 calls made to the NI-488.2 driver for Windows, and records and

displays information about the calls. You can use the GPIB Spy application to locate and

analyze errors in your application or in the configuration of the NI-488.2 software.

Starting GPIB Spy

Start GPIB Spy by double-clicking on the GPIB Spy icon in the GPIB group in the

Program Manager. This activates GPIB Spy and brings up the main GPIB Spy

window. All NI-488 and NI-488.2 calls made while GPIB Spy is active are recorded in

the main GPIB Spy window. GPIB Spy can be turned on and off by choosing SpyOn

from the Spy menu. When GPIB Spy is on, the caption on the main GPIB Spy window

is "GPIB Spy (recording)." When GPIB Spy is off, the caption is "GPIB Spy."

Figure 6-1 shows the main GPIB Spy window with several NI-488 calls recorded in it.

Figure 6-1. Main GPIB Spy Window

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GPIB Spy

Chapter 6

Exiting GPIB Spy

Exit GPIB Spy by choosing Exit from the Spy menu.

Caution: When you exit GPIB Spy, all of the recorded information is lost. See the

section in this chapter entitled GPIB Spy Output Options if you want to avoid

losing the information.

Viewing Call Details

To see detailed information about calls recorded in GPIB Spy, use the Call Details

window. You can activate the Call Details window in two different ways. If you

double-click on any recorded call in the main GPIB Spy window, the call details for that

particular call are displayed in the Call Details window. You can also select the View

Details option from the Spy menu, which makes the Call Details window the top-level

window.

You can use the Call Details window in two ways. If you check the Continuously item

in the View menu, the Call Details window is updated as each new GPIB is recorded and

you cannot scroll through the details for each recorded call. If you uncheck the

Continuously item in the View menu, you can use the <Page Up> or <Page Down> keys

to scroll through the call details of all recorded calls. If a call to the driver produces a

GPIB error condition, the corresponding Call Details window displays an iberr Help

button. Clicking on this button launches an interactive help utility which helps you

identify and correct the problem.

Figure 6-2 shows the GPIB Spy Call Details window for the NI-488 function, ibwrt.

Figure 6-2. GPIB Spy Call Details Window for ibwrt

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GPIB Spy

GPIB Spy Configuration Options

Calls To Highlight

You can choose for GPIB Spy to highlight certain calls based on bits set in ibsta. If

you want to modify this option then select the Calls to Highlight menu item from the

Configure menu. Use the dialog box to select which ibstabits should cause a

recorded call to be highlighted in the main GPIB Spy window. The default configuration

of GPIB Spy is to highlight NI-488 and NI-488.2 calls which return with the ERR bit set

in ibsta.

Calls To Trap On

You can configure GPIB Spy to suspend the execution of an application when one of the

selected trap bits is set in ibsta for the NI-488 or NI-488.2 call that is completing. If

you want to modify this option, select the Calls to Trap On menu item from the

Configure menu. When a call causes a trap to occur, a dialog box pops up and gives a

brief description of the trapped call. A dialog box causes all Windows applications

currently running to be suspended until you click on the OK button. By default, GPIB

Spy does not trap on any calls.

Buffer History

When GPIB Spy records a call such as ibrd, ibwrt, or Send, that includes a buffer of

data, the Call Details window shows you the contents of the buffer. The default

configuration of GPIB Spy is to store each I/O buffer in a brief format. If you want to

modify this option then select the Buffer History menu item from the Configure menu.

The buffer history has three settings: brief, full, and none. These settings determine how

much of the buffer to save for the NI-488 or NI-488.2 call being recorded. Once a call is

recorded, you cannot modify its buffer history. The brief buffer setting saves up to

64 bytes of buffer information. If the buffer is longer than 64 bytes, only the first

32 bytes and last 32 bytes of the buffer are saved. The none buffer setting saves no

buffer information. The full buffer setting saves the entire I/O buffer. Note that the full

buffer setting is likely to degrade the performance of your application and the whole

windows system, especially if the application is transferring large GPIB buffers.

Set Highlight Color

You can use this option to configure the highlight color which is used to highlight

information in the GPIB Spy windows. To change the highlight color, select the Set

Highlight Color menu item from the Configure menu. This causes the standard

Windows color selection dialog box to pop up. Choose a new color and click on OK.

The default highlight color is red.

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GPIB Spy

Chapter 6

Store Configuration

You can use this option to make the current GPIB Spy configuration the default GPIB

Spy configuration. If you want to set the default GPIB Spy configuration, select the

Store Configuration menu item from the Configure menu.

GPIB Spy Output Options

To Screen

You can use this option to select the number of NI-488 and NI-488.2 calls that are

displayed in GPIB Spy. By default GPIB Spy displays 100 calls. Only the most recent

information is stored so that when the number of recorded calls exceeds the limit the

oldest information is discarded. To change the number of calls displayed, select the

To Screen menu item from the Output menu. Then enter the new number and click OK

to save the change.

To File

You can use this option to specify an output file in which to save the information

currently recorded in GPIB Spy. To save the information to a file, select the To File

menu item from the Output menu. This causes the standard Windows file selection

dialog box to pop up. Select a drive, directory and file name in which to save the

information. When you click OK , the information recorded in GPIB Spy is saved to the

specified file.

Check the Update Continuously check box in the dialog box if you want the GPIB Spy

information to be saved as soon as it is recorded. The output file is opened, written, and

closed as each NI-488 or NI-488.2 call is recorded. This option is useful if you are trying

to debug a Windows application that causes the system to crash before you get an

opportunity to close GPIB Spy. Use this option only if you need to because it is likely to

slow down all Windows applications. In addition, if you are low on disk space, choosing

this option could cause you to run out of disk space. To turn off the continuous update

feature, unselect the Update Continuously check box in the file selection dialog box.

Clear Screen

This option clears the display and the information stored in GPIB Spy. You cannot

retrieve information that has been cleared.

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GPIB Spy

GPIB Spy Help

You can access online help for GPIB Spy by selecting the GPIB Spy Help menu item

from the Help menu. All of the information covered in this chapter is available through

the online help. The online help contains a thorough description of each of the features

of GPIB Spy, as well as information to help you develop your Windows GPIB

application.

Performance Considerations

Keep in mind that GPIB Spy can slow down the performance of your GPIB application

and the whole windows system operating environment. If you record full I/O buffers,

update to an output file continuously, or configure GPIB Spy to record the information on

a large number of GPIB calls, it might have a significant effect on performance. For this

reason, use GPIB Spy only while you are debugging your application or in situations in

which performance is not critical.

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Chapter 7

GPIB Programming Techniques

This chapter describes techniques for using some NI-488 functions and NI-488.2 routines

in your application program.

For more detailed information about each function or routine, refer to the NI-488.2

Function Reference Manual for DOS/Windows.

Termination of Data Transfers

GPIB data transfers are terminated either when the GPIB EOI line is asserted with the

last byte of a transfer or when a preconfigured end-of-string (EOS) character is

transmitted. By default, the NI-488.2 driver asserts EOI with the last byte of writes and

the EOS modes are disabled.

You can use the ibeot function to enable or disable the end of transmission (EOT)

mode. If EOT mode is enabled, the NI-488.2 driver asserts the GPIB EOI line when the

last byte of a write is sent out on the GPIB. If it is disabled, the EOI line is not asserted

with the last byte of a write.

You can use the ibeos function to enable, disable, or configure the EOS modes. EOS

mode configuration includes the following information:

•

A 7-bit or 8-bit EOS byte

EOS comparison method–This indicates whether the EOS byte has seven or eight

significant bits. For a 7-bit EOS byte, the eighth bit of the EOS byte is ignored.

•

EOS write method–If this is enabled, the NI-488.2 driver automatically asserts the

GPIB EOI line when the EOS byte is written to the GPIB. If the buffer passed into an

ibwrt call contains five occurrences of the EOS byte, the EOI line is asserted as

each of the five EOS bytes are written to the GPIB. If an ibwrtbuffer does not

contain an occurrence of the EOS byte, the EOI line is not asserted (unless the EOT

mode is enabled, in which case the EOI line is asserted with the last byte of the write).

EOS read method–If this is enabled, the NI-488.2 driver terminates ibrd, ibrda,

and ibrdf calls when the EOS byte is detected on the GPIB, when the GPIB EOI

line is asserted, or when the specified count is reached. If the EOS read method is

disabled, ibrd, ibrda, and ibrdf calls terminate only when the GPIB EOI line is

asserted or the specified count has been read.

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You can use the ibconfig function to configure the software to inform you whether or

not the GPIB EOI line was asserted when the EOS byte was read. Use the

IbcEndBitIsNormaloption to configure the software to report only the END bit in

ibsta when the GPIB EOI line is asserted. By default, the NI-488.2 driver reports END

in ibsta when either the EOS byte is read in or the EOI line is asserted during a read.

High-Speed Data Transfers (HS488)

National Instruments has designed a high-speed data transfer protocol for IEEE 488

called HS488. This protocol increases performance for GPIB reads and writes up to

8 Mbytes/s, depending on your system.

HS488 is a superset of the IEEE 488 standard; thus, you can mix IEEE 488.1,

IEEE 488.2, and HS488 devices in the same system. If HS488 is enabled, the

TNT4882C hardware implements high-speed transfers automatically when

communicating with HS488 instruments. To determine whether your GPIB interface

board has the TNT4882C hardware, use the GPIBInfoutility. If you attempt to enable

HS488 on a GPIB board that does not have the TNT4882C chip, the error ECAP is

returned.

Enabling HS488

To enable HS488 for your GPIB board, use the ibconfigfunction (option

IbcHSCableLength). The value passed to ibconfigshould specify the number of

meters of cable in your GPIB configuration. If you specify a cable length that is much

smaller than what you actually use, the transferred data could become corrupted. If you

specify a cable length longer than what you actually use, the data is transferred

successfully, but more slowly than if you specified the correct cable length.

In addition to using ibconfig to configure your GPIB board for HS488, the Controller-

In-Charge must send out GPIB command bytes (interface messages) to configure other

devices for HS488 transfers.

If you are using device-level calls, the NI-488.2 software automatically sends the HS488

configuration message to devices. If you enabled the HS488 protocol in wibconf, the

NI-488.2 software sends out the HS488 configuration message when you use ibdevto

bring a device online. If you call ibconfigto change the GPIB cable length, the

NI-488.2 software sends out the HS488 message again the next time you call a device-

level function.

If you are using board-level functions or NI-488.2 routines and you want to configure

devices for high-speed, you must send the HS488 configuration messages using ibcmd

or SendCmds. The HS488 configuration message is made up of two GPIB command

bytes. The first byte, the Configure Enable (CFE) message (hex 1F), places all HS488

devices into their configuration mode. Non-HS488 devices should ignore this message.

The second byte is a GPIB secondary command that indicates the number of meters of

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GPIB Programming Techniques

cable in your system. It is called the Configure (CFGn) message. Because HS488 can

operate only with cable lengths of 1 to 15 meters, only CFGn values of 1 through 15 (hex

61 through 6F) are valid. If the cable length was configured correctly in wibconf, you

can determine how many meters of cable are in your system by calling ibask(option

IbaHSCableLength) in your application program. For CFE and CFGn messages,

refer to Appendix A, Multiline Interface Messages, in the NI-488.2 Function Reference

Manual for DOS/Windows.

System Configuration Effects on HS488

Maximum data transfer rates can be limited by your host computer and GPIB

system setup. For example, even though the theoretical maximum transfer rate

with HS488 is 8 Mbytes/s, the maximum transfer rate obtainable on PC compatible

computers with an ISA bus is 2 Mbytes/s. The same IEEE 488 cabling constraints

for a 350 ns T1 delay apply to HS488. As you increase the amount of cable in

your GPIB configuration, the maximum data transfer rate using HS488 decreases.

For example, two HS488 devices connected by two meters of cable can transfer

data faster than three HS488 devices connected by four meters of cable.

Waiting for GPIB Conditions

You can use the ibwait function to obtain the current ibsta value or to suspend your

application until a specified condition occurs on the GPIB. If you use ibwaitwith a

parameter of zero, it immediately updates ibstaand returns. If you want to use

ibwait to wait for one or more events to occur, then pass a wait mask to the function.

The wait mask should always include the TIMO event; otherwise, your application is

suspended indefinitely until one of the wait mask events occurs.

Device-Level Calls and Bus Management

The NI-488 device-level calls are designed to perform all of the GPIB management for

your application program. However, the NI-488.2 driver can handle bus management

only when the GPIB interface board is CIC (Controller-In-Charge). Only the CIC is able

to send command bytes to the devices on the bus to perform device addressing or other

bus management activities. Use one of the following methods to make your GPIB board

the CIC:

•

If your GPIB board is configured as the System Controller (default), it automatically

makes itself the CIC by asserting the IFC line the first time you make a device-level

call.

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•

If your setup includes more than one Controller, or if your GPIB interface board is not

configured as the System Controller, use the CIC Protocol method. To use the

protocol, issue the ibconfigfunction (option IbcCICPROT) or use the wibconf

configuration utility to activate the CIC protocol. If the interface board is not CIC and

you make a device-level call with the CIC Protocol enabled, the following sequence

occurs:

1. The GPIB interface board asserts the SRQ line.

2. The current CIC serial polls the board.

3. The interface board returns a response byte of hex 42.

4. The current CIC passes control to the GPIB board.

If the current CIC does not pass control, the NI-488.2 driver returns the ECIC error

code to your application. This error can occur if the current CIC does not understand

the CIC Protocol. If this happens, you could send a device-specific command

requesting control for the GPIB board. Then use a board-level ibwaitcommand to

wait for CIC.

Talker/Listener Applications

Although designed for Controller-In-Charge applications, you can also use the NI-488.2

software in most non-Controller situations. These situations are known as

Talker/Listener applications because the interface board is not the GPIB Controller. A

typical Talker/Listener application waits for commands from the Controller and responds

as appropriate. The following paragraphs describe some programming techniques for

Talker/Listener applications.

Waiting for Messages from the Controller

A Talker/Listener application typically uses ibwait with a mask of 0 to monitor the

status of the interface board. Then, based on the status bits set in ibsta, the application

takes whatever action is appropriate. For example, the application could monitor the

status bits TACS (Talker Active State) and LACS (Listener Active State) to determine

when to send data to or receive data from the Controller. The application could also

monitor the DCAS (Device Clear Active State) and DTAS (Device Trigger Active State)

bits to determine if the Controller has sent the device clear (DCL or SDC) or trigger

(GET) messages to the interface board. If the application detects a device clear from the

Controller, it might reset the internal state of message buffers. If it detects a trigger

message from the Controller, the application might begin an operation such as taking a

voltage reading if the application is actually acting as a voltmeter.

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Using the Event Queue

Some applications need to know the order in which certain messages are sent by the

Controller. To monitor the ordering of these messages, your application program must

enable the EVENT bit, using ibconfig(option IbcEventQueue). When the

EVENT bit is enabled, the DCAS and DTAS bits are no longer activated. Instead, all

DCAS and DTAS messages are stored in a queue, in the order that they are received.

The event queue also stores interface clear (IFC) messages. When the queue contains

some information, the NI-488.2 software sets the EVENT bit in ibsta. When the

application program detects EVENT, it can call the function ibeventto retrieve the

first event that occurred. Retrieving events from the queue ensures that the application

can respond to device clear, device trigger, and interface clear messages in the correct

order.

Requesting Service

Another type of event that might be important in a Talker/Listener application is the

serial poll. A Talker/Listener application can call ibrsvwith a serial poll response byte

when it needs to request service from the Controller. If the application needs to know

when the Controller has read the serial poll response byte, it can enable the SPOLL bit in

ibsta using ibconfig, option IbcSPollBit. The NI-488.2 software sets the

SPOLL bit when the Controller serial polls the board.

Serial Polling

You can use serial polling to obtain specific information from GPIB devices when they

request service. When the GPIB SRQ line is asserted, it signals the Controller that a

service request is pending. The Controller must then determine which device asserted the

SRQ line and respond accordingly. The most common method for SRQ detection and

servicing is the serial poll. This section describes how you can set up your application to

detect and respond to service requests from GPIB devices.

Service Requests from IEEE 488 Devices

IEEE 488 devices request service from the GPIB Controller by asserting the GPIB SRQ

line. When the Controller acknowledges the SRQ, it serial polls each open device on the

bus to determine which device requested service. Any device requesting service returns a

status byte with bit 6 set and then unasserts the SRQ line. Devices not requesting service

return a status byte with bit 6 cleared. Manufacturers of IEEE 488 devices use lower

order bits to communicate the reason for the service request or to summarize the state of

the device.

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Chapter 7

Service Requests from IEEE 488.2 Devices

The IEEE 488.2 standard refined the bit assignments in the status byte. In addition to

setting bit 6 when requesting service, IEEE 488.2 devices also use two other bits to

specify their status. Bit 4, the Message Available bit (MAV), is set when the device is

ready to send previously queried data. Bit 5, the Event Status bit (ESB), is set if one or

more of the enabled IEEE 488.2 events occurs. These events include power-on, user

request, command error, execution error, device-dependent error, query error, request

control, and operation complete. The device can assert SRQ when ESB or MAV are set,

or when a manufacturer-defined condition occurs.

Automatic Serial Polling

You can enable automatic serial polling if you want your application to conduct a serial

poll automatically any time the SRQ line is asserted. The autopolling procedure occurs

as follows:

1. To enable autopolling, use the configuration utility, wibconf, or the configuration

function, ibconfigwith option IbcAUTOPOLL. (Autopolling is enabled by

default.)

2. When the SRQ line is asserted, the driver automatically serial polls the open devices.

3. Each positive serial poll response (bit 6 or hex 40 is set) is stored in a queue

associated with the device that sent it. The RQS bit of the device status word,

ibsta, is set.

4. The polling continues until SRQ is unasserted or an error condition is detected.

5. To empty the queue, use the ibrspfunction. ibrspreturns the first queued

response. Other responses are read in first-in-first-out (FIFO) fashion. If the RQS

bit of the status word is not set when ibrspis called, a serial poll is conducted and

returns whatever response is received. You should empty the queue as soon as an

automatic serial poll occurs, because responses might be discarded if the queue is

full.

6. If the RQS bit of the status word is still set after ibrsp is called, the response byte

queue contains at least one more response byte. If this happens, you should continue

to call ibrsp until RQS is cleared.

Stuck SRQ State

If autopolling is enabled and the GPIB interface board detects an SRQ, the driver serial

polls all open devices connected to that board. The serial poll continues until either SRQ

unasserts or all the devices have been polled.

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If no device responds positively to the serial poll, or if SRQ remains in effect because of

a faulty instrument or cable, a stuck SRQ state is in effect. If this happens during an

ibwait for RQS, the driver reports the ESRQ error. If the stuck SRQ state happens, no

further polls are attempted until an ibwaitfor RQS is made. When ibwaitis issued,

the stuck SRQ state is terminated and the driver attempts a new set of serial polls.

Autopolling and Interrupts

If autopolling and interrupts are both enabled, the NI-488.2 software can perform

autopolling after any device-level NI-488 call as long as no GPIB I/O is currently in

progress. This means that an automatic serial poll can occur even when your application

is not making any calls to the NI-488.2 software. Autopolling can also occur when a

device-level ibwaitfor RQS is in progress. Autopolling is not allowed whenever an

application calls a board-level NI-488 function or any NI-488.2 routine, or the stuck SRQ

(ESRQ) condition occurs.

If autopolling is enabled and interrupts are disabled, you can use autopolling in the

following situations only:

•

During a device-level ibwaitfor RQS

Immediately after a device-level NI-488 function is completed, before control is

returned to the application program

SRQ and Serial Polling with NI-488 Device Functions

You can use the device-level NI-488 function ibrspto conduct a serial poll. ibrsp

conducts a single serial poll and returns the serial poll response byte to the application

program. If automatic serial polling is enabled, the application program can use ibwait

to suspend program execution until RQS appears in the status word, ibsta. The

program can then call ibrspto obtain the serial poll response byte.

The following example illustrates the use of the ibwaitand ibrsp functions in a

typical SRQ servicing situation when automatic serial polling is enabled.

#include "decl.h"

char GetSerialPollResponse ( int DeviceHandle )

{

char SerialPollResponse = 0;

ibwait ( DeviceHandle, TIMO | RQS );

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if ( ibsta & RQS ) {

printf ( "Device asserted SRQ.\n" );

/* Use ibrsp to retrieve the serial poll

response. */

ibrsp ( DeviceHandle, &SerialPollResponse );

}

return SerialPollResponse;

}

SRQ and Serial Polling with NI-488.2 Routines

The NI-488.2 software includes a set of NI-488.2 routines that you can use to conduct

SRQ servicing and serial polling. Routines pertinent to SRQ servicing and serial polling

are AllSpoll, FindRQS, ReadStatusByte, TestSRQ, and WaitSRQ.

AllSpoll can serial poll multiple devices with a single call. It places the status bytes

from each polled instrument into a predefined array. Then you must check the RQS bit

of each status byte to determine whether that device requested service.

ReadStatusByteis similar to AllSpoll, except that it serial polls only a single

device. It is also analogous to the device-level NI-488 ibrsp function.

FindRQS serial polls a list of devices until it finds a device that is requesting service or

until it has polled all of the specified devices. The routine returns the index and status

byte value of the device requesting service.

TestSRQ determines whether the SRQ line is asserted or unasserted, and returns to the

program immediately.

WaitSRQis similar to TestSRQ, except that WaitSRQsuspends the application

program until either SRQ is asserted or the timeout period is exceeded.

The following examples use NI-488.2 routines to detect SRQ and then determine which

device requested service. In these examples three devices are present on the GPIB at

addresses 3, 4, and 5, and the GPIB interface is designated as bus index 0. The first

example uses FindRQSto determine which device is requesting service and the second

example uses AllSpollto serial poll all three devices. Both examples use WaitSRQ

to wait for the GPIB SRQ line to be asserted.

Note: Automatic serial polling is not used in these examples because you cannot use

it with NI-488.2 routines.

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Chapter 7

GPIB Programming Techniques

Example 1: Using FindRQS

This example illustrates the use of FindRQSto determine which device is requesting

service.

void GetASerialPollResponse ( char *DevicePad,

char *DeviceResponse )

{

char SerialPollResponse = 0;

int WaitResult;

Addr4882_t Addrlist[4] = {3,4,5,NOADDR};

WaitSRQ (0, &WaitResult);

if (WaitResult) {

printf ("SRQ is asserted.\n");

/* Use FindRQS to find a device that requested service. */

FindRQS ( 0, AddrList, &SerialPollResponse );

if (!(ibsta & ERR)) {

printf ("Device at pad %x returned byte %x.\n",

AddrList[ibcnt],(int) SerialPollResponse);

*DevicePad = AddrList[ibcnt];

*DeviceResponse = SerialPollResponse;

}

return;

}

Example 2: Using AllSpoll

This example illustrates the use of AllSpollto serial poll three devices.

void GetAllSerialPollResponses ( Addr4882_t AddrList[], short

ResponseList[] )

{

int WaitResult;

WaitSRQ (0, &WaitResult);

if ( WaitResult ) {

printf ( "SRQ is asserted.\n" );

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GPIB Programming Techniques

Chapter 7

/* Use Allspoll to serial poll all the devices at once. */

AllSpoll ( 0, AddrList, ResponseList );

if (!(ibsta & ERR)) {

for ( i = 0; AddrList[i] != NOADDR; i++ ) {

printf ("Device at pad %x returned byte %x.\n",

AddrList[i], ResponseList[i] );

}

return;

}

Parallel Polling

Although parallel polling is not widely used, it is a useful method for obtaining the status

of more than one device at the same time. The advantage of a parallel poll is that it can

easily check up to eight individual devices at once. In comparison, eight separate serial

polls would be required to check eight devices for their serial poll response bytes.

Implementing a Parallel Poll

You can implement parallel polling with either NI-488 functions or NI-488.2 routines. If

you use NI-488.2 routines to execute parallel polls, you do not need extensive knowledge

of the parallel polling messages. However, you should use the NI-488 functions for

parallel polling when the GPIB board is not the Controller and must configure itself for a

parallel poll and set its own individual status bit (ist).

Parallel Polling with NI-488 Functions

Follow these steps to implement parallel polling using NI-488 functions. Each step

contains example code.

1. Configure the device for parallel polling using the ibppc function, unless the device

can configure itself for parallel polling.

ibppc requires an 8-bit value to designate the data line number, the ist sense, and

whether or not the function configures or unconfigures the device for the parallel

poll. The bit pattern is as follows:

0 1 1 E S D2 D1 D0

E is 1 to disable parallel polling and 0 to enable parallel polling for that particular

device.

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S is 1 if the device is to assert the assigned data line when ist = 1, and 0 if the

device is to assert the assigned data line when ist = 0.

D2 through D0 determine the number of the assigned data line. The physical line

number is the binary line number plus one. For example, DIO3 has a binary bit

pattern of 010.

The following example code configures a device for parallel polling using NI-488

functions. The device asserts DIO7 if its ist= 0.

In this example, the ibdevcommand is used to open a device that has a primary

address of 3, has no secondary address, has a timeout of 3 s, asserts EOI with the last

byte of a write operation, and has EOS characters disabled.

#include "decl.h"

char ppr;

dev = ibdev(0,3,0,T3s,1,0);

/* Pass the binary bit pattern, 0110 0110 or hex 66, to

ibppc */

ibppc(dev, 0x66);

If the GPIB interface board configures itself for a parallel poll, you should still use

the ibppc function. Pass the board index or a board unit descriptor value as the

first argument in ibppc. In addition, if the individual status bit (ist) of the board

needs to be changed, use the ibistfunction.

In the following example, the GPIB board is to configure itself to participate in a

parallel poll. It asserts DIO5 when ist = 1 if a parallel poll is conducted.

ibppc(0, 0x6C);

ibist(0, 1);

2. Conduct the parallel poll using ibrpp and check the response for a certain value.

The following example code performs the parallel poll and compares the response to

hex 10, which corresponds to DIO5. If that bit is set, the ist of the device is 1.

ibrpp(dev, &ppr);

if (ppr & 0x10) printf("ist = 1\n");

3. Unconfigure the device for parallel polling with ibppc. Notice that any value

having the parallel poll disable bit set (bit 4) in the bit pattern disables the

configuration, so you can use any value between hex 70 and 7E.

ibppc(dev, 0x70);

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GPIB Programming Techniques

Chapter 7

Parallel Polling with NI-488.2 Routines

Follow these steps to implement parallel polling using NI-488.2 routines. Each step

contains example code.

1. Configure the device for parallel polling using the PPollConfigroutine, unless

the device can configure itself for parallel polling. The following example

configures a device at address 3 to assert data line 5 (DIO5) when its ist value is 1.

#include "decl.h"

char response;

Addr4882_t AddressList[2];

/* The following command clears the GPIB. */

SendIFC(0);

/* The value of sense is compared with the ist bit of the

device and determines whether the data line is asserted.*/

PPollConfig(0,3,5,1);

2. Conduct the parallel poll using PPoll, store the response, and check the response

for a certain value. In the following example, because DIO5 is asserted by the

device if ist = 1, the program checks bit 4 (hex 10) in the response to determine

the value of ist.

PPoll(0, &response);

/* If response has bit 4 (hex 10) set, the ist bit of the

device at that time is equal to 1. If it does not appear,

the ist bit is equal to 0. Check the bit in the following

statement. */

if (response & 0x10) {

printf("The ist equals 1.\n");

}

else {

printf("The ist equals 0.\n");

}

3. Unconfigure the device for parallel polling using the PPollUnconfigroutine as

shown in the following example. In this example, the NOADDR constant must appear

at the end of the array to signal the end of the address list. If NOADDRis the only

value in the array, all devices receive the parallel poll disable message.

AddressList[0] = 3;

AddressList[1] = NOADDR;

PPollUnconfig(0, AddressList);

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Chapter 8

wibconf–Windows Interface Bus

Configuration Utility

This chapter contains a description of wibconf, the software configuration program you

can use to configure the NI-488.2 software for Windows.

Overview

The wibconfutility is a screen-oriented, interactive program you can use to view or

modify the configuration parameters of your GPIB interface boards and the GPIB devices

connected to them. Usually, you use wibconfto modify the hardware settings of your

GPIB interface boards.

The wibconfutility can read in and display configuration parameters for the NI-488.2

driver file on disk. You can then save the changes back to the disk file. wibconfalso

has a supplementary batch mode which can be used for configuring in a non-interactive

fashion.

Instead of using wibconf, you can configure your driver programmatically by using the

ibconfig function to alter any of the board or device characteristics while your

program is running. If you use dynamic configuration, you do not need to run wibconf

before you start your application. Also, you can run your application on any computer

with the appropriate NI-488.2 software regardless of its configuration because the

application configures the driver as necessary. Programmatic configuration is the

preferred method of GPIB application development.

Starting wibconf

The simplest way to use wibconfis to double-click on the wibconf icon in your

GPIB group in the Windows Program Manager. Windows pops up a dialog box

labeled Parameters.

By default, wibconf looks for the NI-488.2 software configuration file, gpib.ini, in

the c:\windowsdirectory. If you installed Windows in a directory other than

c:\windows, specify the full path to the gpib.inifile in the Parameters box. For

example, if you installed Windows in the directory d:\win3, type

d:\win3\gpib.iniin the Parameters dialog box.

If you installed Windows in the default directory, simply press <Return>.

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Chapter 8

Table 8-1 lists the options you can select when you start wibconf.

Table 8-1. Options for Starting wibconf

wibconf Option

Action

driver

Configure a specific driver.

wibconf configures the given driver configuration file (for

example, wibconf d:\win3\gpib.ini).

-h

Help.

This option causes wibconf to display a summary of options.

-b filename

Batch mode configuration.

wibconf is run in batch mode using the configuration

information contained in the given file (for example, wibconf

-b gpib.cfg). See the wibconf Batch Mode section later in

this chapter.

-e

Expert mode.

This option disables wibconfwarning messages when you exit

wibconf. See the Exiting wibconf section later in this chapter.

-m

Monochrome mode.

This option causes wibconf to run in monochrome mode even if

you have a color monitor.

-vb

Video access through BIOS.

This option causes wibconf to use the system BIOS routines

when writing to the screen. This is slower than the default of

direct screen access, but is more compatible with certain

nonstandard systems.

Upper and Lower Levels of wibconf

wibconf operates at both an upper and a lower level. The upper level consists of the

device map that gives a graphical picture of the GPIB system. The lower level consists

of screens describing the individual boards and devices that make up the system.

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wibconf-Windows Interface Bus Configuration Utility

Upper-Level Device Map

Figure 8-1 shows the upper level of wibconf.

Figure 8-1. Upper Level of wibconf

As shown in Figure 8-1, the upper-level screen of wibconf displays the names of all

devices controlled by the driver. It also indicates which devices, if any, are accessed

through each interface board. You can move around the map by using the cursor control

keys or the mouse.

The following options are available at the upper level.

•

Device maps of the boards

Help

Rename

(Dis)connect

Edit

Exit

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Chapter 8

Device Maps of

the Boards

Use <PageUp> or <PageDown> to toggle between the device maps

for the different GPIB interface boards. These boards are referred

to as access boards. The maps show which devices are assigned to

each board.

Help

Use the function key <F1> to access the comprehensive, online

help feature of wibconf. The help information describes the

functions and common terms associated with the upper level of

wibconf.

Rename

Use the function key <F4> to rename a device. Move to the device

you want to rename by using the cursor control keys. Press the

<F4> key and enter the new name of the device. The device name

may contain up to eight characters in lowercase or uppercase.

The following restrictions apply when renaming a device:

•

Extensions (.xxx) are not allowed

As specified by DOS, the device name cannot use the following

characters:

[

]

;

•

Do not use the reserved names con or nul for your device

Do not give GPIB device names the same names as files,

directories, or subdirectories. If you name a GPIB device

pltr and your file system contains the file pltr.dator a

subdirectory pltr, a conflict results.

•

The names of the access boards gpib0, gpib1, gpib2, and

gpib3 are fixed and connot be changed.

(Dis)connect

Use the function key <F5> to connect or disconnect a device from

a particular access board. Move the cursor to the device that you

want to connect or disconnect by using the cursor control keys and

then press the <F5> key.

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wibconf-Windows Interface Bus Configuration Utility

Edit

Use the function key <F8> or the <Enter> key to edit or examine

the characteristics of a particular board or device. Move to the

board or device that you want to edit using the cursor control keys

and then press the <F8> key. This step puts you in the lower level

of wibconf and lists the characteristics for the particular board or

device that you want to edit. To exit edit, press the function key

<F9> or <Escape> to return to the upper level.

Exit

Use the function key <F9> or <Escape> to exit wibconf. If you

have made changes, wibconf prompts you to save the changes

before exiting. For more information, refer to the Exiting wibconf

section later in this chapter.

Lower-Level Device/Board Characteristics

The lower-level screens of wibconf display the currently defined values for

characteristics of a device or board such as addressing and timeout information, as shown

in Figure 8-2.

Figure 8-2. Lower Level of wibconf

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wibconf-Windows Interface Bus Configuration Utility

Chapter 8

You can access the lower-level screens from the map level of wibconf by selecting a

board or device and pressing <F8>. You can use the <Up>, <Down>, <PageUp>, and

<PageDown> cursor keys to select a characteristic. For your convenience, cursor control

keys and function keys are defined at the bottom of your computer screen.

Selecting the configuration settings for each device and board customizes the

communications and other options to be used with that board or device. The access board

uses these settings either when device functions are called to program the device or when

board functions are called to program the board.

The following options are available at the lower level.

•

Change Characteristics

Change Board or Device

Help

Reset Value

Return to Map

Change

Characteristics

To change a specific characteristic of a device or a board, move the

cursor to, or click the mouse, on the field for that characteristic.

You can also use <PageUp>, <PageDown>, <Home>, or <End> to

select other characteristics of a device or board. When the cursor

is on the characteristic, either use the left/right arrow keys to select

between different options or input the option directly from the

keyboard. Instructions on the right side of the screen inform you

which method is appropriate for the selected characteristic.

Change Board

or Device

Use <Control-PageUp> and <Control-PageDown> to change to the

next or previous GPIB board or device. For example, if you are

editing dev3 and press <Control-PageUp>, you will then be

editing dev4.

Help

Use the function key <F1> to access the comprehensive, online

help feature of wibconf. The help information describes the

functions and common terms associated with the lower level of

wibconf.

Reset Value

Use the function key <F6> to reset a characteristic option to its

previous value.

Return to Map

At the lower level, the function key <F9> or <Escape> returns you

to the upper-level device map of wibconf.

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wibconf-Windows Interface Bus Configuration Utility

Board and Device Configuration Options

To view detailed information about each characteristic, position the cursor in the field for

that characteristic. For information on characteristics specific to a particular driver,

check the getting started manual that came with your interface board. The following

paragraphs describe the options available in wibconf for the NI-488.2 software for

Windows.

Primary GPIB Address

All devices and boards must be assigned a unique primary address in the range hex 00 to

hex 1E (0 to 30 decimal). The default primary address of all GPIB boards is 0.

The GPIB primary address of any device is set within the device, either with hardware

switches or a by software program. The address set within the device must correspond to

the address in the memory-resident driver. In the NI-488.2 driver for Windows, the

default primary addresses of dev1through dev16, and dev17 through dev32, are 1

through 16, respectively. Refer to the device documentation for instructions about setting

the device address. GPIB boards do not have hardware switches to select the GPIB

address.

The primary GPIB address is used to compute the talk and listen addresses of devices and

boards. The NI-488.2 driver automatically forms a listen address by adding hex 20 to the

primary address and a talk address by adding hex 40 to the primary address. For

example, a primary address of hex 10 has a listen address of hex 30 and a talk address of

hex 50.

Secondary GPIB Address

Any device or board using extended addressing must be assigned a secondary address in

the range hex 60 to hex 7E (96 to 126 decimal), or you can select NONEto disable

secondary addressing.

As with primary addressing, the secondary GPIB address of a device is set within that

device, either with hardware switches or by a software program. The address set within

the device must correspond to the address in the memory-resident driver. Refer to the

device documentation for instructions about secondary addressing. The default setting

for this characteristic is NONEfor all boards and devices.

Timeout Setting

The timeout value is the approximate length of time that GPIB functions wait for data to

be transferred or commands to be sent. It is also the length of time that the ibwait

function waits for an event before returning, if the TIMO bit is set in the event mask. For

example, if the SRQI bit and TIMO bit in the event mask are passed to the ibwait

function and no SRQ is detected, then the function times out after the timeout period has

elapsed. The default option for this characteristic is 10 s.

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Chapter 8

Serial Poll Timeouts (Device Characteristic Only)

This timeout value controls the length of time the driver waits for a serial poll response

from a device. The IEEE 488.1 specification does not specify the length of time a

Controller should wait for the response byte. The default of 1 s should work for most

devices. If you seem to have problems with serial polls, try using a longer timeout value.

Terminate Read on EOS

Some devices send an EOS byte signaling the last byte of a data message. A yes

response in this field causes the GPIB board to terminate a read operation when it

receives the EOS byte. The default option for this characteristic is no.

Set EOI with EOS on Writes

A yes response in this field causes the GPIB board to assert the EOI line when the EOS

byte is detected on a write operation. The default option for this characteristic is no.

Type of Compare on EOS

This field specifies the type of comparison to be made with the EOS byte. You can state

whether to compare all eight bits or just the seven least significant bits, which are in

ASCII or ISO (International Standards Organization) format. The default option for this

characteristic is 7-bit.

Note: This field is only meaningful if a yesresponse was given for either the Set

EOI with EOS on Write field or the Terminate Read on EOS field.

EOS Byte

Some devices can be programmed to terminate a read operation when a selected character

is detected. A linefeed character (hex 0A) is a common EOS byte. The default option for

this characteristic is 00H.

Note: The driver does not automatically append an EOS byte to the end of data

strings on write operations. You must explicitly include this byte in your data

string. The EOS byte is used only so that the driver terminates read

operations properly.

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Send EOI at End of Write

Some devices, as Listeners, require that the Talker terminate a data message by asserting

the EOI line with the last byte. A yesresponse causes the GPIB board to assert the EOI

line on the last data byte. The default option for this characteristic is yes.

System Controller (Board Characteristic Only)

This field appears on the board characteristics screen only. The System Controller in a

GPIB system is the device that maintains ultimate control over the bus. In some

situations, such as a network of computers linked by the GPIB, another device may be

System Controller and the GPIB board should be designated as not System Controller. A

no response would designate not System Controller and a yes response would designate

System Controller capability. The GPIB board is usually designated as System

Controller. The default option for this characteristic is yes.

Note: You should not have more than one designated System Controller in any GPIB

system.

Assert REN when SC (Board Characteristic Only)

A yes response to this field causes Remote Enable (REN) to be asserted automatically

whenever the board is placed online, if that the board has System Controller capability.

If you give a no response, an explicit call to ibsreis required to assert REN. The

default option for this characteristic is no.

Enable Auto Serial Polling (Board Characteristic Only)

This option enables or disables automatic serial polls of devices when the GPIB Service

Request (SRQ) line is asserted. Positive poll responses are stored following the polls and

can be read with the ibrspdevice function. Normally, this feature does not conflict

with devices that conform to the IEEE 488.1 specification. If a conflict exists with a

device, use a no response for this field to disable this feature. The default option for this

characteristic is yes.

Enable CIC Protocol (Board Characteristic Only)

If a device-level NI-488 function is called after control has been passed to another device,

enabling this protocol causes the board to assert SRQ with a Serial Poll status byte of

hex 42. The current Controller must recognize that the board wants to regain control. If

the current Controller passes control back to the board, the device call proceeds as

intended. If control is not passed within the timeout period, or if the CIC protocol is

disabled, the ECIC error is returned. The default option for this characteristic is no.

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Chapter 8

Bus Timing (Board Characteristic Only)

This field specifies the T1 delay of the source handshake capability for the board. This

delay determines the minimum amount of time, after the data is placed on the bus, that

the board may assert DAV during a write or command operation. If the total length of

the GPIB cable length in the system is less than 15 m, the value of 350 ns is appropriate.

Other factors might affect the choice of the T1 delay, although they are unlikely to affect

your system setup. Refer to the ANSI/IEEE Standard 488.1-1987, Section 5.2, for more

information about these other factors. The default for this option is 500 ns.

Cable Length for High Speed (Board Characteristic Only)

This field specifies the number of meters of GPIB cable you have in your system. If you

use the HS488 high-speed protocol to communicate with HS488-compliant devices, you

must specify the total number of meters of GPIB cable in your system. The System

Controller, when it initializes the GPIB, must send this information to all HS488 devices

so that high-speed transfers occur without errors.

Parallel Poll Duration (Board Characteristic Only)

This field specifies the length of time the driver waits when conducting a parallel poll.

For a normal bus configuration (the Controller and devices on the same bus) use the

default duration of 2 µs. If you are using a GPIB bus extender in transparent parallel poll

mode, you should increase the poll duration to 10 µs so that the bus extender can operate

transparently to your applications.

Use This GPIB Interface (Board Characteristic Only)

If you do not want the driver to try to access a board at the selected base address (because

you do not have a board in the system), select nofor this option. When this field is set to

no, the driver returns the EDVR error as soon as a program tries to access the board. By

default, access board gpib0is enabled, and gpib1, gpib2, and gpib3 are disabled.

Base I/O Address (Board Description Only)

This field specifies the I/O address of the GPIB board. It must be set to the same value as

the base I/O address setting for the GPIB board itself. Setting the base I/O address level

is explained in the getting started manual that you received with your GPIB interface

board.

Note: On some systems, this field is read-only and you cannot change it using

wibconf. Refer to your getting started manual for information on how

to change the I/O address.

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wibconf-Windows Interface Bus Configuration Utility

DMA Channel (Board Characteristic Only)

This field specifies the DMA channel used by the GPIB board. It must be set to the same

value as the DMA channel (arbitration level for Micro Channel systems) setting for the

GPIB board itself. Setting the DMA channel is explained in the getting started manual

that you received with your GPIB interface board.

Note: On some systems, you can only enable or disable the use of DMA with the

wibconf utility. You cannot change the DMA channel setting. Refer to your

getting started manual for information on how to change the DMA channel.

Interrupt Jumper Setting (Board Characteristic Only)

This field specifies the interrupt line used by the GPIB board. It must be set to the same

value as the interrupt level setting for the GPIB board itself. Setting the interrupt level is

explained in the getting started manual that you received with your GPIB board.

Note: On some systems, you can only enable or disable the use of interrupts with the

wibconf utility. You cannot change the IRQ request line. Refer to your

getting started manual for information on how to change the interrupt level.

Enable Repeat Addressing (Device Characteristic Only)

Normally, devices are not addressed each time a read or write operation is performed. If

no is selected, read or write operations do not readdress the selected device if the same

operation was just performed with that device. Avoiding readdressing saves some time

when you have several GPIB operations to perform. But it might be a problem for some

older IEEE 488.1 devices that require their GPIB address to be sent with each I/O

operation. Select yesto enable repeat addressing in such a situation. The default option

for this characteristic is no.

GPIB-PCII/IIA Mode Switch

The driver that is included with the GPIB-PCII and GPIB-PCIIA interface board kits is

the same for each kit and can run with both boards. Use this field to indicate the type of

board that is installed in your system. You can have both a GPIB-PCII and a

GPIB-PCIIA interface board installed in your system at the same time.

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Chapter 8

Default Configurations in wibconf

This section lists the default configuration values of the NI-488.2 driver.

•

Thirty-two devices with symbolic names dev1 through dev32.

Four access boards with symbolic names gpib0, gpib1, gpib2, and gpib3. You

cannot change the access board names.

•

Access board gpib0is enabled. gpib1, gpib2, and gpib3 are disabled.

The GPIB addresses of the first 16 devices are the same as the device number. For

example, dev is at address 1. These 16 devices are assigned to the access board

gpib0.

•

The remaining 16 devices (that is, devices 17 through 32) are assigned to the access

board gpib1. Their GPIB addresses range from 1 through 16, respectively. For

example, dev17 is at address 1.

•

Each GPIB interface board is System Controller for its independent bus and has a

GPIB address of 0.

The END message is sent with the last byte of each data message to a device. No

end-of-string (EOS) character is recognized.

•

The timeout value for I/O and wait functions is set for 10 s.

Each GPIB board and device is set to perform I/O transfers using DMA.

Automatic serial polling is enabled.

At the end of each NI-488.2 routine, the NI-488.2 driver leaves the bus in its currently

addressed state (IEEE 488.2 standard).

Exiting wibconf

After you have made all your changes, you can exit wibconf by pressing <F9> or

<Esc>. The program prompts you to save the changes. Select Yesto save the changes,

No to discard the changes, or cancel to remain in wibconf.

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8-12

Chapter 8

wibconf-Windows Interface Bus Configuration Utility

Checking for Errors

Unless you started in expert mode, wibconfchecks for possible problems before

quitting. It alerts you to situations such as the following:

•

GPIB addressing conflict between a device and its access board

GPIB boards not present in the host machine at the specified address

Timeouts disabled on a device or board

To disable automatic checking when starting wibconf, use the -e option.

wibconf Batch Mode

The wibconfbatch mode offers an alternative method for modifying the configurations

of the NI-488.2 driver. Batch mode can also modify the loaded driver.

In batch mode, the configuration information is contained in a configuration file that you

create. To use the configuration file that you created, enter the following command:

wibconf -b filename

where filename is the name of the configuration file. You must include at least one

space between -b and filename.

The configuration file is a free-form text file consisting of pairs of items. Each item must

be separated by at least one space or new line character. The first item of a pair is a

mnemonic that represents a board or device characteristic or a device map configuration

function (for example, rename, connect, disconnect) to be configured. The

second item of a pair is the value to which the first item (mnemonic) should be set.

Before configuring a board or device, that board or device must be found by the find

name# pair, where nameis board or deviceand #is the index of the GPIB board or

device you are configuring.

When wibconf is run in batch mode, it checks the syntax of the first item in the pair

and the value range of the second item, and it reports any errors as it finds them. If a

value range error is found, the correct range of values is displayed. If any errors are

found, the driver is not configured.

8-13

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wibconf-Windows Interface Bus Configuration Utility

Chapter 8

The following example is a sample configuration file followed by an explanation of each

entry.

find device1 name plotter

find device2 disconnect

find device3 connect board1

find board0 pad 2 tmo 30sec eos 0x1E sc no

bin 8-bit tmng 350nsec

This example makes the following changes:

1. Change the name of the first device to plotter.

2. Disconnect the second device.

3. Connect the third device to board 1 (gpib1).

4. Change the configuration of board 0 (gpib0).

•

Primary address to 2 (pad 2)

Timeout setting to 30 s (tmo 30sec)

EOS byte to hex 1E (eos 0x1E)

System Controller capability to NO (sc no)

Type of compare on EOS to 8-bit (bin 8-bit)

GPIB bus timing to 350 ns (tmng 350nsec)

Table 8-2 contains a list of the valid pairs of items. You can enter number values as

decimal or hexadecimal. Hexadecimal numbers must be preceded with 0x. For

example, decimal 64 would be written as 0x40. For more information about valid input

values, refer to the relevant function descriptions in the NI-488.2 Function Reference

Manual for DOS/Windows.

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8-14

Chapter 8

wibconf-Windows Interface Bus Configuration Utility

Table 8-2. wibconf Batch Mode Command Pairs

First Item

Explanation

Second Item

Mnemonic

find

pad

Find board or device

board# or device#

number

Primary GPIB address

sad

Secondary GPIB address

Timeout settings

number

tmo

mnemonic

xeos

bin

Set EOI with EOS on write

Type of compare on EOS

Set EOI with last byte of write

System Controller (board only)

Assert REN when SC (board only)

Enable auto serial polling (board only)

Timing (board only)

yes or no

7-bitor 8-bit

yes or no

eot

yes or no

sre

yes or no

spoll

tmng

yes or no

2msec, 500nsec, or

350nsec

cic prot

CIC protocol (board only)

yes or no

number

int

Interrupt setting (board only)

Base I/O address (board only)

DMA channel (board only)

port

number

dma

number

raddr

name

Repeat addressing (device only)

Rename a device (device only)

Connect a device to a board (device only)

yes or no

device name

board#

no value

connect

disconnect

Disconnect a device from a board (device

only)

type

Switch the current board to PCII or PCIIA

mode

PCII or PCIIA

pplength

useboard

spolltmo

Parallel poll duration (board only)

Use this interface board (board only)

Serial Poll Timeout (device only)

mnemonic

yes or no

mnemonic

8-15

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Appendix A

Status Word Conditions

This appendix gives a detailed description of the conditions reported in the status word,

ibsta.

For information about how to use ibsta in your application program, refer to Chapter 3,

Developing Your Application.

If a function call returns an ENEB or EDVR error, all status word bits except the ERR bit

are cleared, indicating that it is not possible to obtain the status of the GPIB board.

Each bit in ibsta can be set for device calls (dev), board calls (brd), or both (dev, brd).

The following table lists the status word bits.

Table A-1. Status Word Bits

Bit

Hex

Value

Mnemonic Pos.

Type

Description

ERR

8000

4000

2000

1000

800

dev, brd GPIB error

TIMO

END

dev, brd Time limit exceeded

dev, brd END or EOS detected

SRQI

RQS

brd

dev

brd

SRQ interrupt received

Device requesting service

SPOLL

400

Board has been serial polled by

Controller

EVENT

CMPL

LOK

200

100

brd

DCAS, DTAS, or IFC event has occurred

dev, brd I/O completed

brd

Lockout State

REM

Remote State

CIC

Controller-In-Charge

Attention is asserted

Talker

ATN

TACS

LACS

DTAS

DCAS

Listener

Device Trigger State

Device Clear State

A-1

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Status Word Conditions

Appendix A

ERR (dev, brd)

ERR is set in the status word following any call that results in an error. You can

determine the particular error by examining the error variable iberr. Appendix B,

Error Codes and Solutions, describes error codes that are recorded in iberr along with

possible solutions. ERR is cleared following any call that does not result in an error.

TIMO (dev, brd)

TIMO indicates that the timeout period has been exceeded. TIMO is set in the status

word following an ibwaitcall if the TIMO bit of the ibwaitmask parameter is set

and the time limit expires. TIMO is also set following any synchronous I/O functions

(for example, ibcmd, ibrd, ibwrt, Receive, Send, and SendCmds) if a timeout

occurs during one of these calls. TIMO is cleared in all other circumstances.

END (dev, brd)

END indicates either that the GPIB EOI line has been asserted or that the EOS byte has

been received, if the software is configured to terminate a read on an EOS byte. If the

GPIB board is performing a shadow handshake as a result of the ibgts function, any

other function can return a status word with the END bit set if the END condition occurs

before or during that call. END is cleared when any I/O operation is initiated.

Some applications might need to know the exact I/O read termination mode of a read

operation–EOI by itself, the EOS character by itself, or EOI plus the EOS character. You

can use the ibconfigfunction (option IbcEndBitIsNormal) to enable a mode in

which the END bit is set only when EOI is asserted. In this mode, if the I/O operation

completes because of the EOS character by itself, END is not set. The application should

check the last byte of the received buffer to see if it is the EOS character.

SRQI (brd)

SRQI indicates that a GPIB device is requesting service. SRQI is set whenever the GPIB

board is CIC, the GPIB SRQ line is asserted, and the automatic serial poll capability is

disabled. SRQI is cleared either when the GPIB board ceases to be the CIC or when the

GPIB SRQ line is unasserted.

RQS (dev)

RQS appears in the status word only after a device-level call. It indicates that one or

more serial poll response bytes are waiting in the device’s serial poll response queue.

Automatic serial poll responses are not stored in the response queue unless they have

bit 6 set.

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A-2

Appendix A

Status Word Conditions

An automatic serial poll occurs either as a result of a call to ibwait, or automatically, if

automatic serial polling is enabled. If the serial poll response queue is not empty, ibrsp

returns the oldest byte stored in the queue. To empty the response queue, call ibrsp

repeatedly until RQS is no longer set in the device's status word.

SPOLL (brd)

Use SPOLL in Talker/Listener applications to determine when the Controller has serial

polled the GPIB board. The SPOLL bit is disabled by default. Use the ibconfig

function (option IbcSPollBit) to enable it. When this bit is enabled, it is set after the

board has been polled. SPOLL is cleared on any call immediately after an ibwaitcall,

if the SPOLL bit was set in the wait mask, or immediately following a call to ibrsv.

EVENT (brd)

Use EVENT in Talker/Listener applications (applications in which the GPIB interface is

not the Controller) to monitor the order of GPIB device clear, group execute trigger, and

send interface clear commands. The usual DCAS and DTAS bits of ibstamight be

insufficient.

The EVENT bit is disabled by default. If you want to use this bit, you must use the

ibconfigfunction (option IbcEventQueue) to enable it. When you enable this bit,

the DCAS and DTAS bits are disabled. When an event occurs, this bit is set and any I/O

in progress is aborted. The application can then call the ibeventfunction to determine

which event occurred.

CMPL (dev, brd)

CMPL indicates the condition of I/O operations. It is set whenever an I/O operation is

complete. CMPL is cleared while the I/O operation is in progress.

LOK (brd)

LOK indicates whether the board is in a lockout state. While LOK is set, the

EnableLocalroutine or ibloc function is inoperative for that board. LOK is set

whenever the GPIB board detects that the Local Lockout (LLO) message has been sent

either by the GPIB board or by another Controller. LOK is cleared when the System

Controller unasserts the Remote Enable (REN) GPIB line.

A-3

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Status Word Conditions

Appendix A

REM (brd)

REM indicates whether or not the board is in the remote state. REM is set whenever the

Remote Enable (REN) GPIB line is asserted and the GPIB board detects that its listen

address has been sent either by the GPIB board or by another Controller. REM is cleared

in the following situations:

•

When REN becomes unasserted

When the GPIB board as a Listener detects that the Go to Local (GTL) command has

been sent either by the GPIB board or by another Controller

•

When the ibloc function is called while the LOK bit is cleared in the status word

CIC (brd)

CIC indicates whether the GPIB board is the Controller-In-Charge. CIC is set when the

SendIFCroutine or ibsic function is executed either while the GPIB board is System

Controller or when another Controller passes control to the GPIB board. CIC is cleared

either when the GPIB board detects Interface Clear (IFC) from the System Controller or

when the GPIB board passes control to another device.

ATN (brd)

ATN indicates the state of the GPIB Attention (ATN) line. ATN is set whenever the

GPIB ATN line is asserted, and it is cleared when the ATN line is unasserted.

TACS (brd)

TACS indicates whether the GPIB board is addressed as a Talker. TACS is set whenever

the GPIB board detects that its talk address (and secondary address, if enabled) has been

sent either by the GPIB board itself or by another Controller. TACS is cleared whenever

the GPIB board detects the Untalk (UNT) command, its own listen address, a talk address

other than its own talk address, or Interface Clear (IFC).

LACS (brd)

LACS indicates whether the GPIB board is addressed as a Listener. LACS is set

whenever the GPIB board detects that its listen address (and secondary address, if

enabled) has been sent either by the GPIB board itself or by another Controller. LACS is

also set whenever the GPIB board shadow handshakes as a result of the ibgtsfunction.

LACS is cleared whenever the GPIB board detects the Unlisten (UNL) command, its own

talk address, Interface Clear (IFC), or that the ibgts function has been called without

shadow handshake.

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A-4

Appendix A

Status Word Conditions

DTAS (brd)

DTAS indicates whether the GPIB board has detected a device trigger command. DTAS

is set whenever the GPIB board, as a Listener, detects that the Group Execute Trigger

(GET) command has been sent by another Controller. DTAS is cleared on any call

immediately following an ibwait call, if the DTAS bit is set in the ibwaitmask

parameter.

DCAS (brd)

DCAS indicates whether the GPIB board has detected a device clear command. DCAS is

set whenever the GPIB board detects that the Device Clear (DCL) command has been

sent by another Controller, or whenever the GPIB board as a Listener detects that the

Selected Device Clear (SDC) command has been sent by another Controller. DCAS is

cleared on any call immediately following an ibwait call, if the DCAS bit was set in

the ibwait mask parameter. It also occurs on any call immediately following a read or

write.

A-5

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Appendix B

Error Codes and Solutions

This appendix lists a description of each error, some conditions under which it might

occur, and possible solutions.

The following table lists the GPIB error codes.

Table B-1. GPIB Error Codes

Error

Mnemonic

iberr

Value

Meaning

EDVR

ECIC

Windows error

Function requires GPIB board to be CIC

No Listeners on the GPIB

GPIB board not addressed correctly

Invalid argument to function call

GPIB board not System Controller as required

I/O operation aborted (timeout)

Nonexistent GPIB board

ENOL

EADR

EARG

ESAC

EABO

ENEB

EDMA

EOIP

DMA error

Asynchronous I/O in progress

No capability for operation

File system error

ECAP

EFSO

EBUS

ESTB

ESRQ

ETAB

GPIB bus error

Serial poll status byte queue overflow

SRQ stuck in ON position

Table problem

EDVR (0)

EDVR is returned in the following cases:

•

The board or device name passed to ibfindis not configured in the software. In

this case, the variable ibcntl contains the DOS error code 2, Device Not Found.

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Error Codes and Solutions

Appendix B

•

An invalid unit descriptor is passed to any function call. In this case, the variable

ibcntl contains the DOS error code 6, Invalid handle.

•

The driver (gpib.dll) is not installed.

The driver configuration file gpib.iniis not located in the windows directory. In

this case, the variable ibcntl contains the value -1.

•

The driver file gpib.iniis in the windows directory but not compatible with the

driver file gpib.dllthat you are using. In this case, the variable ibcntlcontains

a negative value other than -1.

Solutions

•

Use ibdev to open a device without specifying its symbolic name.

Use only device or board names that are configured in the utility program wibconf

as parameters to the ibfindfunction.

•

Use the unit descriptor returned from ibfindas the first parameter in subsequent

NI-488 functions. Examine the variable before the failing function to make sure the

function has not been corrupted.

Make sure the NI-488.2 driver is installed by checking that gpib.dlland

gpib.iniare in the windows directory (usually c:\windows).

ECIC (1)

ECIC is returned when one of the following board functions or routines is called while

the board is not CIC:

•

Any device-level NI-488 functions that affect the GPIB

Any board-level NI-488 functions that issue GPIB command bytes, such as ibcmd,

ibcmda, ibln, ibrpp

• ibcac, ibgts

•

Any of the NI-488.2 routines that issue GPIB command bytes, such as SendCmds,

PPoll, Send, Receive

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B-2

Appendix B

Error Codes and Solutions

Solutions

•

Use ibsicor SendIFC to make the GPIB board become CIC on the GPIB.

Use ibrsc 1to make sure your GPIB board is configured as System Controller.

In multiple CIC situations, always be certain that the CIC bit appears in the status

word ibsta before attempting these calls. If it does not appear, you can perform an

ibwait (for CIC) call to delay further processing until control is passed to the board.

ENOL (2)

ENOL usually occurs when a write operation is attempted with no Listeners addressed.

For a device write, this error indicates that the GPIB address configured for that device in

the software does not match the GPIB address of any device connected to the bus, that

the GPIB cable is not connected to the device, or that the device is not powered on.

ENOL can also occur in situations in which the GPIB board is not the CIC and the

Controller asserts ATN before the write call in progress has ended.

Solutions

•

Make sure that the GPIB address of your device matches the GPIB address of the

device to which you want to write data.

•

Use the appropriate hex code in ibcmdto address your device.

Check your cable connections and make sure at least two-thirds of your devices are

powered on.

•

Call ibpad(or ibsad, if necessary) to match the configured address to the device

switch settings.

Reduce the write byte count to that which is expected by the Controller.

EADR (3)

EADR occurs when the GPIB board is CIC and is not properly addressing itself before

read and write functions. This error is usually associated with board-level functions.

EADR is also returned by the function ibgtswhen the shadow-handshake feature is

requested and the GPIB ATN line is already unasserted. In this case, the shadow

handshake is not possible and the error is returned to notify you of that fact.

B-3

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Error Codes and Solutions

Appendix B

Solutions

•

Make sure that the GPIB board is addressed correctly before calling ibrd, ibwrt,

RcvRespMsg, or SendDataBytes.

•

Avoid calling ibgtsexcept immediately after an ibcmdcall. ibcmd causes ATN

to be asserted.

EARG (4)

EARG results when an invalid argument is passed to a function call. The following are

some examples:

• ibtmo called with a value not in the range 0 through 17

• ibpad or ibsad called with invalid addresses

• ibppc called with invalid parallel poll configurations

•

A board-level NI-488 call made with a valid device descriptor, or a device-level

NI-488 call made with a board descriptor.

•

An NI-488.2 routine called with an invalid address.

• PPollConfigcalled with an invalid data line or sense bit.

Solutions

•

Make sure that the parameters passed to the NI-488 function or NI-488.2 routine are

valid.

•

Do not use a device descriptor in a board function or vice-versa.

ESAC (5)

ESAC results when ibsic, ibsre, SendIFC, or EnableRemoteis called when the

GPIB board does not have System Controller capability.

Solutions

Give the GPIB board System Controller capability by calling ibrsc 1 or by using

wibconf to configure that capability into the software.

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B-4

Appendix B

Error Codes and Solutions

EABO (6)

EABO indicates that an I/O operation has been canceled, usually due to a timeout

condition. Other causes for this error are calling ibstop or receiving the Device Clear

message from the CIC while performing an I/O operation.

Frequently, the I/O is not progressing (the Listener is not continuing to handshake or the

Talker has stopped talking), or the byte count in the call which timed out was more than

the other device was expecting.

Solutions

•

Use the correct byte count in input functions or have the Talker use the END message

to signify the end of the transfer.

•

Lengthen the timeout period for the I/O operation using ibtmo.

Make sure that you have configured your device to send data before you request data.

ENEB (7)

ENEB occurs when no GPIB board exists at the I/O address specified in the configuration

program. This happens when the board is not physically plugged into the system, the I/O

address specified during configuration does not match the actual board setting, there is a

system conflict with the base I/O address, or the Use This GPIB Interfacefield

in wibconf is not set correctly.

Solutions

•

Make sure there is a GPIB board in your computer that is properly configured both in

hardware and software using a valid base I/O address.

•

Make sure that the Use This GPIB Interfacefield in wibconf is set to Yes.

EDMA (8)

EDMA is returned when an error occurs using DMA for data transfers. If your computer

has more than 16 MB of RAM and you do not have the National Instruments virtual

GPIB device (nivgpibd.386) installed, the NI-488.2 software returns EDMA if you

are using DMA and the data buffer is located in memory above 16 MB.

B-5

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Error Codes and Solutions

Appendix B

If you are using Windows 3.0 with DMA for data transfers, and you do not have the

National Instruments virtual DMA device (nivdmad.386) installed, the NI-488.2

software returns EDMA if you try to use DMA to transfer data.

Solutions

•

Install the appropriate virtual device in the system.inifile in the Windows

directory in the [386Enh] section. The following line installs the virtual GPIB

device:

device = drive:\path\nivgpib.386

where drive and path describe the location of nivgpib.386on your hard drive.

•

By default, only one GPIB board at a time can perform DMA. If you need to perform

DMA transfers on multiple GPIB boards at the same time, add a new section to your

system.inifile, [vgpibd]. In this section add the option

NumBoardsUsingDMAand set it equal to the number of boards that will be

performing DMA. For example, if you want two boards to perform DMA

concurrently, add the following lines to the bottom of your system.inifile:

[vgpibd]

NumBoardsUsingDMA=2

• To install the virtual DMA device, first change the default virtual DMA device line to a

remark line by adding a semicolon. Then add a line to install the National Instruments

virtual DMA device as follows:

;device = *vdmad

device = drive:\path\nivdmad.386

where drive and path describe the location of nivdmad.386on your hard drive.

Note: You must restart Windows after you modify the system.inifile.

• Alternatively, you can correct the EDMA problem by disabling DMA in the software.

You can use ibdma to disable DMA.

EOIP (10)

EOIP occurs when an asynchronous I/O operation has not finished before some other call

is made. During asynchronous I/O, you can only use ibstop, ibwait, and ibonlor

perform other non-GPIB operations. Once the asynchronous I/O has begun, further GPIB

calls other than ibstop, ibwait, or ibonl are strictly limited. If a call might

interfere with the I/O operation in progress, the driver returns EOIP.

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B-6

Appendix B

Error Codes and Solutions

Solutions

Resynchronize the driver and the application before making any further GPIB calls.

Resynchronization is accomplished by using one of the following three functions:

• ibwait

If the returned ibsta contains CMPL then the driver and application

are resynchronized.

• ibstop

The I/O is canceled; the driver and application are resynchronized.

• ibonl

The I/O is canceled and the interface is reset; the driver and application

are resynchronized.

ECAP (11)

ECAP results when your GPIB board lacks the ability to carry out an operation or when a

particular capability has been disabled in the software and a call is made that requires the

capability.

Solutions

Check the validity of the call, or make sure your GPIB interface board and the driver both

have the needed capability.

EFSO (12)

EFSO results when an ibrdf or ibwrtf call encounters a problem performing a file

operation. Specifically, this error indicates that the function is unable to open, create,

seek, write, or close the file being accessed. The specific DOS error code for this

condition is contained in ibcntl.

Solutions

•

Make sure the filename, path, and drive that you specified are correct.

Make sure that the access mode of the file is correct.

Make sure there is enough room on the disk to hold the file.

B-7

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Error Codes and Solutions

Appendix B

EBUS (14)

EBUS results when certain GPIB bus errors occur during device functions. All device

functions send command bytes to perform addressing and other bus management.

Devices are expected to accept these command bytes within the time limit specified by

the default configuration or the ibtmo function. EBUS results if a timeout occurred

while sending these command bytes.

Solutions

•

Verify that the instrument is operating correctly.

•

Check for loose or faulty cabling or several powered-off instruments on the GPIB.

If the timeout period is too short for the driver to send command bytes, increase the

timeout period.

ESTB (15)

ESTB is reported only by the ibrspfunction. ESTB indicates that one or more serial

poll status bytes received from automatic serial polls have been discarded because of a

lack of storage space. Several older status bytes are available; however, the oldest is

being returned by the ibrsp call.

Solutions

•

Call ibrsp more frequently to empty the queue.

Disable autopolling with the ibconfigfunction or the wibconfutility.

ESRQ (16)

ESRQ occurs only during the ibwaitfunction or the WaitSRQ routine. ESRQ

indicates that a wait for RQS is not possible because the GPIB SRQ line is stuck on. This

situation can be caused by the following events:

•

Usually, a device unknown to the software is asserting SRQ. Because the software

does not know of this device, it can never serial poll the device and unassert SRQ.

•

A GPIB bus tester or similar equipment might be forcing the SRQ line to be asserted.

A cable problem might exist involving the SRQ line.

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B-8

Appendix B

Error Codes and Solutions

Although the occurrence of ESRQ warns you of a definite GPIB problem, it does not

affect GPIB operations, except that you cannot depend on the RQS bit while the

condition lasts.

Solutions

Check to see if other devices not used by your application are asserting SRQ. Disconnect

them from the GPIB if necessary.

ETAB (20)

ETAB occurs only during the FindLstn, FindRQS, and ibevent functions. ETAB

indicates that there was some problem with a table used by these functions.

•

In the case of FindLstn, ETAB means that the given table did not have enough

room to hold all the addresses of the Listeners found.

In the case of FindRQS, ETAB means that none of the devices in the given table

were requesting service.

In the case of ibevent, ETAB means the event queue overflowed and event

information was lost.

Solutions

In the case of FindLstn, increase the size of result arrays. In the case of FindRQS,

check to see if other devices not used by your application are asserting SRQ. Disconnect

them from the GPIB if necessary. In the case of ETAB returned from ibevent, call

ibeventmore often to empty the queue.

B-9

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Appendix C

Customer Communication

For your convenience, this appendix contains forms to help you gather the information

necessary to help us solve technical problems you might have as well as a form you can

use to comment on the product documentation. Filling out a copy of the Technical

Support Form before contacting National Instruments helps us help you better and faster.

National Instruments provides comprehensive technical assistance around the world. In

the U.S. and Canada, applications engineers are available Monday through Friday from

8:00 a.m. to 6:00 p.m. (central time). In other countries, contact the nearest branch

office. You may fax questions to us at any time.

Corporate Headquarters

(512) 795-8248

Technical support fax:

(800) 328-2203

(512) 794-5678

Branch Offices

Australia

Austria

Belgium

Canada (Ontario)

Canada (Quebec)

Denmark

Finland

Phone Number

03 9 879 9422

0662 45 79 90 0

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519 622 9310

514 694 8521

45 76 26 00

90 527 2321

1 48 14 24 24

089 741 31 30

2645 3186

02 48301892

03 5472 2970

02 596 7456

95 800 010 0793

0348 433466

32 84 84 00

Fax Number

03 9 879 9179

0662 45 79 90 19

02 757 03 11

519 622 9311

514 694 4399

45 76 71 11

90 502 2930

1 48 14 24 14

089 714 60 35

2686 8505

02 48301915

03 5472 2977

02 596 7455

5 520 3282

0348 430673

32 84 86 00

France

Germany

Hong Kong

Italy

Japan

Korea

Mexico

Netherlands

Norway

Singapore

Spain

Sweden

Switzerland

Taiwan

U.K.

2265886

2265887

91 640 0085

08 730 49 70

056 200 51 51

02 377 1200

01635 523545

91 640 0533

08 730 43 70

056 200 51 55

02 737 4644

01635 523154

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NI-488.2 User Manual for Windows

Technical Support Form

Photocopy this form and update it each time you make changes to your software or

hardware, and use the completed copy of this form as a reference for your current

configuration. Completing this form accurately before contacting National

Instruments for technical support helps our applications engineers answer your

questions more efficiently.

If you are using any National Instruments hardware or software products related to this

problem, include the configuration forms from their user manuals. Include additional

pages if necessary.

Name

Company

Address

Fax (

)

Phone (

)

Computer brand

Model

Processor

Operating system

Speed

MHz

RAM

Display adapter

Mouse

yes

Other adapters installed

Hard disk capacity

Instruments used

Brand

National Instruments hardware product model

Revision

Configuration

(continues)

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National Instruments software product

Version

Configuration

The problem is

List any error messages

The following steps will reproduce the problem

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Documentation Comment Form

National Instruments encourages you to comment on the documentation supplied with

our products. This information helps us provide quality products to meet your needs.

Title: NI-488.2^™User Manual for Windows

Edition Date:

Part Number:

January 1996

370902A-01

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Thank you for your help.

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Mail to:

Technical Publications

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(512) 794-5678

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Glossary

Prefix

Meaning

Value

-9

nano-

micro-

milli-

kilo-

-6

µ-

-3

M-

mega-

acceptor handshake

Listeners use this GPIB interface function to receive data, and

all devices use it to receive commands. See source handshake

and handshake.

access board

The GPIB board that controls and communicates with the

devices on the bus that are attached to it.

ANSI

American National Standards Institute.

ASCII

American Standard Code for Information Interchange.

asynchronous

An action or event that occurs at an unpredictable time with

respect to the execution of a program.

automatic serial polling A feature of the NI-488.2 software in which serial polls

(autopolling)

are executed automatically by the driver whenever a device

asserts the GPIB SRQ line.

base I/O address

BIOS

See I/O address.

Basic Input/Output System.

board-level function

A rudimentary function that performs a single operation.

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Glossary

CFE

Configuration Enable is the GPIB command which precedes

CFGn and is used to place devices into their configuration

mode.

CFGn

CIC

These GPIB commands (CFG1 through CFG15) follow CFE

and are used to configure all devices for the number of meters

of cable in the system so that HS488 transfers occur without

errors.

See Controller-In-Charge.

Controller-In-Charge

(CIC)

The device that manages the GPIB by sending interface

messages to other devices.

CPU

Central processing unit.

DAV (Data Valid)

DCL

One of the three GPIB handshake lines. See handshake.

Device Clear is the GPIB command used to reset the device or

internal functions of all devices. See SDC.

Device Clear

See DCL.

device-level function

A function that combines several rudimentary board

operations into one function so that the user does not have to

be concerned with bus management or other GPIB protocol

matters.

DIO1 through DIO8

The GPIB lines that are used to transmit command or data

bytes from one device to another.

DLL

Dynamic link library.

DMA

High-speed data transfer between the GPIB

(direct memory access) board and memory that is not handled directly by the CPU.

Not available on some systems. See programmed I/O.

driver

Device driver software installed within the operating system.

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Glossary-2

Glossary

END or END message

A message that signals the end of a data string. END is sent

by asserting the GPIB End or Identify (EOI) line with the last

data byte.

EOI

A GPIB line that is used to signal either the last byte of a data

message (END) or the parallel poll Identify (IDY) message.

EOS or EOS byte

A 7- or 8-bit end-of-string character that is sent as the last byte

of a data message.

EOT

ESB

End of transmission.

The Event Status bit is part of the IEEE 488.2-defined status

byte which is received from a device responding to a serial

poll.

GET

Group Execute Trigger is the GPIB command used to trigger a

device or internal function of an addressed Listener.

Go To Local

GPIB

See GTL.

General Purpose Interface Bus is the common name for the

communications interface system defined in ANSI/IEEE

Standard 488.1-1987 and ANSI/IEEE Standard 488.2-1987.

GPIB address

The address of a device on the GPIB, composed of a primary

address (MLA and MTA) and an optional secondary address

(MSA). The GPIB board has both a GPIB address and an I/O

address.

GPIB board

Refers to the National Instruments family of GPIB interface

boards.

Group Executed Trigger See GET.

GTL

Go To Local is the GPIB command used to place an addressed

Listener in local (front panel) control mode.

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Glossary

handshake

The mechanism used to transfer bytes from the Source

Handshake function of one device to the Acceptor Handshake

function of another device. The three GPIB lines DAV,

NRFD, and NDAC are used in an interlocked fashion to signal

the phases of the transfer, so that bytes can be sent

asynchronously (for example, without a clock) at the speed of

the slowest device.

For more information about handshaking, refer to the

ANSI/IEEE Standard 488.1-1987.

hex

Hexadecimal; a number represented in base 16, for example

decimal 16 = hex 10.

high-level function

See device-level function.

Hertz.

ibcnt

After each NI-488.2 I/O function, this global variable contains

the actual number of bytes transmitted.

iberr

ibsta

A global variable that contains the specific error code

associated with a function call that failed.

At the end of each function call, this global variable (status

word) contains status information.

IEEE

Institute of Electrical and Electronic Engineers.

interface message

A broadcast message sent from the Controller to all devices

and used to manage the GPIB.

I/O (Input/Output)

I/O address

ist

In the context of this manual, the transmission of commands

or messages between the computer via the GPIB board and

other devices on the GPIB.

The address of the GPIB board from the point of view of the

CPU, as opposed to the GPIB address of the GPIB board.

Also called port address or board address.

An Individual Status bit of the status byte used in the Parallel

Poll Configure function.

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Glossary-4

Glossary

Kilobytes.

LAD (Listen Address)

language interface

See MLA.

Code that enables an application program that uses NI-488

functions or NI-488.2 routines to access the driver.

listen address

Listener

See MLA .

A GPIB device that receives data messages from a Talker.

low-level function

See board-level function.

Meters.

MAV

The Message Available bit is part of the IEEE 488.2-defined

status byte which is received from a device responding to a

serial poll.

Megabytes of memory.

Resident in RAM.

memory-resident

MLA

(My Listen Address)

A GPIB command used to address a device to be

a Listener. It can be any one of the 31 primary addresses.

MSA

My Secondary Address is the GPIB command used to address

(My Secondary Address) a device to be a Listener or a Talker when extended (two byte)

addressing is used. The complete address is a MLA or MTA

address followed by an MSA address. There are 31 secondary

addresses for a total of 961 distinct listen or talk addresses for

devices.

MTA (My Talk Address) A GPIB command used to address a device to be a Talker. It

can be any one of the 31 primary addresses.

multitasking

The concurrent processing of more than one program or task.

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Glossary

NDAC

(Not Data Accepted)

One of the three GPIB handshake lines. See

handshake.

NRFD

(Not Ready For Data)

One of the three GPIB handshake lines. See

handshake.

parallel poll

The process of polling all configured devices at once and

reading a composite poll response. See serial poll.

PIO

PPC

See programmed I/O.

Parallel Poll Configure is the GPIB command

(Parallel Poll Configure) used to configure an addressed Listener to participate in polls.

PPD

Parallel Poll Disable is the GPIB command used

to disable a configured device from participating in polls.

There are 16 PPD commands.

(Parallel Poll Disable)

PPE

Parallel Poll Enable is the GPIB command used

to enable a configured device to participate in polls and to

assign a DIO response line. There are 16 PPE commands.

(Parallel Poll Enable)

PPU

(Parallel Poll

Unconfigure)

Parallel Poll Unconfigure is the GPIB command

used to disable any device from participating in

polls.

programmed I/O

Low-speed data transfer between the GPIB board and memory

in which the CPU moves each data byte according to program

instructions. See DMA.

RAM

Random-access memory.

resynchronize

The NI-488.2 software and the user application must

resynchronize after asynchronous I/O operations have

completed.

RQS

Request Service.

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Glossary-6

Glossary

Seconds.

SDC

Selected Device Clear is the GPIB command used to reset

internal or device functions of an addressed Listener. See

DCL and IFC.

serial poll

The process of polling and reading the status byte of one

device at a time. See parallel poll.

Service Request

source handshake

See SRQ.

The GPIB interface function that transmits data and

commands. Talkers use this function to send data, and the

Controller uses it to send commands. See acceptor handshake

and handshake.

SPD

Serial Poll Disable is the GPIB command used to

cancel an SPE command.

(Serial Poll Disable)

SPE

Serial Poll Enable is the GPIB command used to

enable a specific device to be polled. That device must also be

addressed to talk. See SPD.

(Serial Poll Enable)

SRQ (Service Request) The GPIB line that a device asserts to notify the CIC that the

device needs servicing.

status byte

The IEEE 488.2-defined data byte sent by a device when it is

serially polled.

status word

See ibsta.

synchronous

Refers to the relationship between the NI-488.2 driver

functions and a process when executing driver functions is

predictable; the process is blocked until the driver completes

the function.

System Controller

The single designated Controller that can assert control

(become CIC of the GPIB) by sending the Interface Clear

(IFC) message. Other devices can become CIC only by

having control passed to them.

Glossary-7 NI-488.2 User Manual for Windows

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Glossary

TAD (Talk Address)

See MTA.

Talker

TCT

A GPIB device that sends data messages to Listeners.

Take Control is the GPIB command used to pass control of the

bus from the current Controller to an addressed Talker.

timeout

TLC

A feature of the NI-488.2 driver that prevents I/O functions

from hanging indefinitely when there is a problem on the

GPIB.

An integrated circuit that implements most of the GPIB

Talker, Listener, and Controller functions in hardware.

ud (unit descriptor)

A variable name and first argument of each function call that

contains the unit descriptor of the GPIB interface board or

other GPIB device that is the object of the function.

UNL

UNT

Unlisten is the GPIB command used to unaddress any active

Listeners.

Untalk is the GPIB command used to unaddress an active

Talker.

wibconf

wibic

The NI-488.2 driver configuration program for Windows.

The Interface Bus Interactive Control program for Windows is

used to communicate with GPIB devices, troubleshoot

problems, and develop your application.

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Glossary-8

Index

Symbols

! (repeat previous function) function, wibic, 5-15

$ (execute indirect file) function, wibic, 5-16

+ (turn display on) function, wibic, 5-15

- (turn display off) function, wibic, 5-15

Active Controller. See Controller-in-Charge (CIC).

addresses. See GPIB addresses.

AllSpoll routine, 7-8, 7-9 to 7-10

ANSI/IEEE Standard 488.1-1987. See GPIB.

application development. See also debugging.

accessing NI-488.2 DLL, 3-1

application examples

asynchronous I/O, 2-6 to 2-7

basic communication, 2-2 to 2-3

basic communication with IEEE 488.2-compliant devices, 2-14 to 2-15

clearing and triggering devices, 2-4 to 2-5

end-of-string mode, 2-8 to 2-9

non-controller example, 2-20 to 2-21

parallel polls, 2-18 to 2-19

serial polls using NI-488.2 routines, 2-16 to 2-17

service requests, 2-10 to 2-13

source code files, 2-1

choosing between NI-488 functions and NI-488.2 routines, 3-1 to 3-3

compiling, linking, and running applications

Borland C++, 3-17

direct entry with C, 3-22

direct entry with Visual Basic, 3-23

Microsoft C, 3-17

Visual Basic applications, 3-18

global variables for checking status, 3-3 to 3-5

count variables - ibcnt and ibcntl, 3-5

error variable - iberr, 3-5

status word - ibsta, 3-3 to 3-4

NI-488 applications

clearing devices, 3-8

configuring devices, 3-9

flowchart of programming with device-level functions, 3-7

general steps and examples, 3-8 to 3-10

items to include, 3-6

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Index

opening devices, 3-8

placing device offline, 3-10

processing of data, 3-10

program shell (illustration), 3-7

reading measurement, 3-10

triggering devices, 3-9

waiting for measurement, 3-9 to 3-10

NI-488 functions, 3-2 to 3-3

advantages, 3-2

board functions, 3-2 to 3-3

device functions, 3-2

one device per board, 3-2 to 3-3

NI-488.2 applications

configuring instruments, 3-15

finding all Listeners, 3-13

flowchart of programming with routines, 3-12

general steps and examples, 3-13 to 3-16

identifying instruments, 3-13 to 3-14

initialization, 3-13

initializing instruments, 3-14

items to include, 3-11

placing board offline, 3-16

processing of data, 3-16

program shell (illustration), 3-12

reading measurement, 3-16

triggering instruments, 3-15

waiting for measurement, 3-15 to 3-16

NI-488.2 routines, 3-3

wibic for communicating with devices, 3-5

asynchronous I/O application example, 2-6 to 2-7

ATN (attention) line, 1-3

ATN status word condition

bit position, hex value, and type (table), 3-4

description, A-4

automatic serial polling. See serial polling.

auxiliary functions, wibic

! (repeat previous function), 5-15

$ (execute indirect file), 5-16

+ (turn display on), 5-15

- (turn display off), 5-15

buffer (set buffer display mode), 5-17

help (display help information), 5-15

n* (repeat function n times), 5-16

print (display the ASCII string), 5-17

set (select device or board), 5-15

table of functions, 5-14

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Index-2

Index

base I/O address, setting, 8-10

batch mode for wibconf utility, 8-13 to 8-15

command pairs (table), 8-15

configuration file, 8-13 to 8-14

board configuration. See wibconf utility.

board functions. See NI-488 functions.

boards

disabling access to GPIB board, 8-10

testing with wibtest, 4-1 to 4-2

Borland C++. See C language.

buffer command (set buffer display mode), 5-17

buffer history, viewing, 6-3

bus timing, setting, 8-10

C language

compiling, linking, and running applications, 3-17

direct entry, 3-18 to 3-22

files available with NI-488.2 software, 1-7

cables

checking with wibtest, 4-2

setting cable length for high-speed data transfers, 8-10

Call Details window, GPIB Spy utility, 6-2

calls

highlighting, 6-3

trapping, 6-3

CIC. See Controller-in-Charge (CIC).

CIC protocol

enabling, 8-9

making GPIB board Controller-in-Charge, 7-3 to 7-4

CIC status word condition

bit position, hex value, and type (table), 3-4

description, A-4

clearing and triggering devices, example, 2-4 to 2-5

CMPL status word condition

bit position, hex value, and type (table), 3-4

description, A-3

communication application examples

basic communication, 2-2 to 2-3

with IEEE 488.2-compliant devices, 2-14 to 2-15

communication errors, 4-6

repeat addressing, 4-6

termination method, 4-6

Index-3

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Index

compiling, linking, and running applications

Borland C++, 3-17

direct entry with C, 3-18 to 3-22

direct entry with Visual Basic, 3-23

Microsoft C, 3-17

Visual Basic, 3-18

configuration, 1-4 to 1-6. See also GPIB Spy utility; wibconf utility.

controlling more than one board, 1-5

linear and star system configuration (illustration), 1-4

requirements, 1-5 to 1-6

configuration errors, 4-5 to 4-6

configuration file for wibconf batch mode, 8-13 to 8-14

Configure (CFGn) message, 7-2

Configure Enable (CFE) message, 7-2

Controller-in-Charge (CIC)

Active Controller as CIC, 1-1

CIC protocol, 7-3, 8-9

configuring GPIB board as CIC, 7-3 to 7-4, 8-9

System Controller as, 1-1

Controllers

definition, 1-1

emulation of non-controller GPIB, example, 2-20 to 2-21

idle Controller, 1-1

System Controller, 1-1, 8-9

count, in wibic, 5-10

count variables - ibcnt and ibcntl, 3-5

customer communication, xvi, C-1

data lines, 1-2

data transfers

high-speed (HS488), 7-2 to 7-3

enabling, 7-2 to 7-3

system configuration effects, 7-3

terminating, 7-1 to 7-2

DAV (data valid) line, 1-3

DCAS status word condition

bit position, hex value, and type (table), 3-4

description, A-5

monitoring for messages from Controller, 7-4

debugging. See also GPIB Spy utility.

common questions, 4-7 to 4-8 to 4-9

communication errors, 4-6

repeat addressing, 4-6

termination method, 4-6

configuration errors, 4-5 to 4-6

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Index-4

Index

global status variables, 4-3

GPIB error codes (table), 4-4 to 4-5

GPIB Spy utility, 4-4

GPIBInfo utility, 4-2 to 4-3

timing errors, 4-6

wibic utility, 4-4

wibtest diagnostics, 4-1 to 4-2

cable connections, 4-2

presence of board, 4-1 to 4-2

presence of driver, 4-1

default configurations in wibconf, 8-12

DevClear routine, 3-14

device configuration. See wibconf utility.

device functions. See NI-488 functions.

device-level calls and bus management, 7-3 to 7-4

direct access to NI-488.2 dynamic link library

compiling, linking, and running applications

using C language, 3-18 to 3-22

using Visual Basic, 3-23

requirements, 3-1

DMA channel, setting, 8-11

documentation

conventions used in manual, xv

organization of manual, xi