Industrial
RS-232 to RS-485/422 Converter
KSC-240
InstallationGuide
DOC.070412-KSC-240
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The information contained in this document is subject to change without
prior notice. Copyright (C) All Rights Reserved.
TRADEMARKS
Ethernet is a registered trademark of Xerox Corp.
FCC NOTICE
This device complies with Class B Part 15 the FCC Rules. Operation is
subject to the following two conditions: (1) This device may not cause
harmful interference, and (2) this device must accept any interference
received including the interference that may cause.
CE NOTICE
Marking by the symbol
indicates compliance of this equipment to
the EMC directive of the European Community. Such marking is indica-
tive that this equipment meets or exceeds the following technical stan-
dards:
EMC Class B
EN 50081-1/1992 : EN55022:1994/A1:1995/A2:1997 Class B
EN61000-3-2:2000
EN61000-3-3:1995/A1:2001
EN 55024:1998/A1:2001
IEC 61000-4-2:1995
IEC 61000-4-3:1995
IEC 61000-4-4:1995
IEC 61000-4-5:1995
IEC 61000-4-6:1996
IEC 61000-4-8:1993
IEC 61000-4-11:1994
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Table of Contents
1. Introduction......................................................... 5
1.1 Features ........................................................................................ 6
1.2 Specifications ................................................................................ 7
2. Installation ......................................................... 12
2.1 Unpacking .................................................................................... 12
2.2 Safety Cautions .......................................................................... 13
2.3 DIN-Rail Mounting ....................................................................... 14
2.4 Panel Mounting ............................................................................ 16
2.5 Applying Power ........................................................................... 18
2.6 Power Failure Relay Output ........................................................ 21
2.7 DIP SW Configuration .................................................................. 22
2.7.1 RS-485/422 Driver and Receiver Control ................................. 28
2.8 Making Serial RS-232 Connection .............................................. 29
2.8.1 Cable for Connection to PC COM Port ..................................... 31
3 Making RS-485/422 Connection ....................... 32
3.1 RS-422 Point-to-Point Circuit ...................................................... 33
3.2 RS-422 Multi-drop Network ......................................................... 34
3.3 RS-485 Multi-drop Network ......................................................... 36
3.4 RS-485 Half-duplex 2-wire Network ............................................ 38
3.5 RS-485 Full-duplex 4-wire Network ............................................ 39
3.6 Summary of the Converter Applications ...................................... 41
4 LED Indicators ................................................... 42
4.1 LED Indicators ............................................................................. 42
5 Factory Default Configuration .......................... 43
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1. Introduction
The industrial converter is designed to convert RS-232 signals to opti-
cally isolated, balanced, full or half-duplex RS-422 or RS-485 signals at
baud rate up to 115.2Kbps. It features RTS control design, which allows
TM
software to control RS-485 transmission. With smart ADC (Auto Data
Control) design, the converter can uses send data signal to control RS-
485 transmission automatically so no software control is required in RS-
485 mode. The Din-rail mountable design makes it ideal for industrial
cabinets and enclosures. Further, more designs such as signal protec-
tion, wide operating temperature range, wide power voltage range are
provided to suit for more industrial applications.
For industrial environment, the converters are designed with the follow-
ing enhanced features exceeding that of commercial media converters:
•
•
•
High and wide operating Temperature
Wide operating voltage range for DC power input
Power input interface: Industrial screw terminal block and DC
power jack for external commercial power adapter as option
•
•
•
DIN rail mounting support for industrial enclosure
Screw panel mounting support for industrial enclosure
Industrial-rated Emission and Immunity performance
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1.1 Features
ꢀ Supports RS-232 baud rate up to 115.2Kbps
ꢀ Operation with no required configuration
ꢀ Provides surge protection (transient voltage) on all interface lines
ꢀ Provides high ESD protection on all line signals
ꢀ Optical isolated between RS-232 and RS-485/422 interfaces
ꢀ Supports RS-422, 2-wire RS-485, and 4-wire RS-485 network
ꢀ Supports full-duplex or half-duplex for RS-485/422 interface
ꢀ Provides remote RTS control for RS-485 transmission
TM
ꢀ ProvidesADC (AutoData Control) for RS-485 transmission
ꢀ Designed for industrial environments with:
- Surge, ESD, and isolation protection
-DIN-rail and panel mounting support
- Wide power voltage range support
- Terminal block and Jack-type power connectors
- Wide operating temperature range support
-Alarm relay output for device power failure
- Industrial-rated emission and immunity performance
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1.2 Specifications
This figure shows the important components of the device:
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Serial Interface (RS-232 Port)
Connector
DB9 female
Pin Assignments
Baud Rate Support
Connector Shield
Connection Distance
High ESDTolerance
DCE type
Up to 115K baud
Connect to chassis ground
15 meters
+/-15KV on Tx, Rx lines
Overvoltage Protection Cutoff if over +/-28V
Isolation
Optical isolation with RS-485/422 interface
RS-485/422 Interface
Connector
Signal Type
Screw-type terminal block
Balanced differential lines
115Kbps
Data Speed
Standard
EIA-485, EIA-422
High ESDTolerance
+/-15KV on driver and receiver lines
Overvoltage Protection Cutoff if over +/-28V
LEDIndicators
LED
DISPLAY
STATE INTERPRETATION
PWR
Power status
ON
Power on
OFF
Power off
232 TX RS-232 TX
232RX RS-232RX
BLINK
BLINK
RS-232 TXActivity
RS-232 RXActivity
RS-485 driver is enabled
RS-485 driver is disabled
TXC
RS-485/422 TX control ON
OFF
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ConfigurationDIPSW Settings
SW
Name State Function
SW1-2&1 4W
2W
Off
On
4-wire (RS-485/422 driver receiver separated)
2-wire (RS-485/422 driver receiver connected)
SW1-3
SW1-4
SW1-5
SW1-6
T -D
T -E
Off
On
Disable RS-485/422 receiver terminator
Enable RS-485/422 receiver terminator
TXC
TXE
Off
On
RS-485/422 driver enable control by RTS or ADC
RS-485/422 driver is forced to enable
RTS-D Off
RTS-E On
Disable RTS control for RS-485/422 TX RX
Enable RTS control for RS-485/422 TX RX
RXC
RXE
Off
On
RS-485/422 receiver enable control by RTS or ADC
RS-485/422 receiver is forced to enable.
SW1-8&7 BIAS-D Off
BIAS-E On
RS-485/422 line bias is disabled
RS-485/422 line bias is enabled
SW2-1
SDD
SDE
Off
On
Disable ADC control for RS-485/422 TX RX
Enable ADC control for RS-485/422 TX RX
SW2-2
SW2-3
SW2-4
SW2-5
SW2-6
SW2-7
SW2-8
1200 On
2400 On
4800 On
9600 On
19200 On
38400 On
115200 On
ADC Timing parameter for RS-232 baud 1200
ADC Timing parameter for RS-232 baud 2400
ADC Timing parameter for RS-232 baud 4800
ADC Timing parameter for RS-232 baud 9600
ADC Timing parameter for RS-232 baud 19200
ADC Timing parameter for RS-232 baud 38400
ADC Timing parameter for RS-232 baud 115200
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DC Power Interface
Interface
Screw-type terminal block
1. Two pairs for power wire cascading
2. One pair for power failure relay output
DCJack(-D6.3mm/+D2.0mm)
Operating Input Voltages +7V~+30V(+5%)
Power consumption
0.6W@+7.5VDC, 12VDC, 30VDC input
Basic Information
Conversion
RS-232 RX data to RS-485/422 TX data
RS-485/422 RX data to RS-232 TX data
Isolated between RS-232 and RS-485/422
3000VDCrms
Optical Isolation
Mechanical
Dimension (base)
Housing
Mounting Support
Weight
W28mmxD82mmxH95mm
Enclosed metal with no fan
DIN-rail mounting, Panel mounting
240g
Environmental
Operating Temperature
Storage Temperature
Relative Humidity
-20oC ~ 70oC
-20oC ~ 85oC
5% ~ 90%
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Certificate
FCC
CE/EMC
Part 15 Class B
EMI EN50081-1 Class B
EMSEN55024
EN60950
CE/LVDSafety
EN 50081-1/1992 :
EN55022:1994/A1:1995/A2:1997
EN61000-3-2:2000
EN61000-3-3:1995/A1:2001
EN 55024:1998/A1:2001
IEC 61000-4-2:1995 ESD Test
IEC 61000-4-3:1995 RS Test
IEC 61000-4-4:1995 EFT/BURST Test
IEC 61000-4-5:1995 Surge Test
IEC 61000-4-6:1996 CS Test
IEC 61000-4-8:1993 Magnetic Field
IEC 61000-4-11:1994 Volatge Int. Dips
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2. Installation
2.1 Unpacking
Check that the following components have been included:
•
•
•
Information CD
The device unit
DIN-rail mounting bracket
If any item is found missing or damaged, please contact your local reseller
for replacement.
The following are available optional accessories:
•
•
Panel Mounting Bracket
The bracket is used for mounting the device on a panel surface.
Commercial-ratedAC power adapters:
- Rated AC120V/60Hz DC7.5V 1A
- Rated AC230V/50Hz DC7.5V 1A
- Rated AC100V/50-60Hz DC7.5V 1A
- Rated AC240V/50Hz DC7.5V 1A
The adapters are used for supplying DC power to the converter
via DC power jack interface.
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2.2 Safety Cautions
To reduce the risk of bodily injury, electrical shock, fire, and damage to
the equipment, observe the following precautions.
• Do not service any product except as explained in your system
documentation.
• Opening or removing covers may expose you to electrical shock.
Only a trained service technician should service components inside
these compartments.
• If any of the following conditions occur, unplug the product from the
electrical outlet and replace the part or contact your trained service
provider:
- The power cable, extension cable, or plug is damaged.
- An object has fallen into the product.
- The product has been exposed to water.
- The product has been dropped or damaged.
- The product does not operate correctly when you follow the
operating instructions.
• Do not push any objects into the openings of your system. Doing
so can cause fire or electric shock by shorting out interior compo-
nents.
• Operate the product only from the type of external power source
indicated on the electrical ratings label. If you are not sure of the
type of power source required, consult your service provider or local
power company.
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2.3 DIN-Rail Mounting
In the product package, a DIN-rail bracket is installed on the device for
mounting the converter in a industrial DIN-rail enclosure.
The steps to mount the device onto a DIN rail are:
1. Install the mounting bracket onto the device unit as shown below:
2. Attach bracket to the lower edge of the DIN rail and push the unit
upward a little bit until the bracket can clamp on the upper edge of
the DIN rail.
3. Clamp the unit to the DIN rail and make sure it is mounted securely.
4. Make sure that there are proper heat dissipation from and adequate
ventilation around the device.
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The final mechanical dimensions after installingDIN rail mounting bracket
are:
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2.4 Panel Mounting
The device is provided with an optional panel mounting bracket. The
bracket support mounting the device on a plane surface securely. The
mounting steps are:
1. Install the mounting bracket on the device unit.
2. Screw the bracket on the device unit.
3. Screw the device unit on a panel.
4. Make sure that there are proper heat dissipation from and adequate
ventilation around the device. Do not place heavy objects on the
device.
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The screw locations and final dimension are shown below:
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2.5 Applying Power
The power specifications of the device are:
Operating Voltage
+7~+30VDC
Power Consumption Max.0.6W@+30VDC,+12VDC,+7.5VDC
The device provides two types of power interfaces, terminal block and DC
power jack for receivingDC power input from external power supply.
Using Terminal Blocks
Either DC1 interface or DC2 interface can be used to receive DC power
from an external power system. Or, DC2 also can be used to deliver the
power received on DC1 to next device in cascading way.
DC1+
DC1-
DC2+
DC2-
Vdc Positive (+) terminal
Vdc Negative (-) terminal
Vdc Positive (+) terminal
Vdc Negative (-) terminal
Three 2P terminal plugs are provided together with the device. Two of the
three plugs are used forDC1 andDC2 interfaces respectively. The plug is
shown below:
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Power wires: 24 ~ 12AWG(IEC 0.5~2.5mm2)
Install the power source wires with the plug properly. Screw the wire with
plug securely. Then, plug in DC1 contacts.
If cascading the power to next device is needed, install the power wires
and plug for another switch. Then, use DC2 contacts.
Note: Only up to four device units can be cascaded to receive power
from one main power input source.
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UsingDC Power Jack
DC Jack Connector: JackD6.3mm
D2.0mm
AC Power Adapters: Optional commercial rated adapters are available
for purchasing.
Rated AC120V/60Hz DC7.5V 1A
Rated AC230V/50Hz DC7.5V 1A
Rated AC100V/50-60Hz DC7.5V 1A
Rated AC240V/50Hz DC7.5V 1A
Connect power adapter DC plug to the DC power jack of the converter
before connecting to the AC outlet. Connect the power adapter to the
AC outlet.
Note: Before you begin the installation, check the AC voltage of your
area. The AC power adapter which is used to supply the DC power
for the unit should have the AC voltage matching the commercial
power voltage in your area.
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2.6 Power Failure Relay Output
The device provides a relay output to report power failure event to a
remote alarm monitoring system. The replay output is provided with two
contacts labeled PF+ and PF- in the terminal block interface.
Use the provided 2Pterminal plug for signal wiring and plug into the PF+/
- contacts. The function is designed as :
Power is normal PF+ contact is shorted with PF- contact.
Power failure
PF+ contact is disconnected with PF- contact.
Note: Be sure the voltage applied on PF+/- contacts is within the
specification of 30VDC/1A max. or 120VAC/0.5A max.
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2.7 DIP SW Configuration
SW1-2 & 1
4W 4-wire (RS-485/422 driver receiver separated)
2W 2-wire (RS-485/422 driver receiver connected)
[2W] setting activates the internal connection between driver and re-
ceiver in RS-485/422 interface. It simplifies the installation of the con-
verter in a 2-wire bus. RS-422 usually uses 2-wire topology only. RS-485
supports both 2-wire and 4-wire topology.
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SW1-3
T-D Disable RS-485/422 receiver terminator
T-E Enable RS-485/422 receiver terminator
[T-E] setting enables the internal 120 ohms terminator on the receiver
interface. A proper termination is important in a bus topology or multi-
drop network. The terminator is a resistor added in parallel with the
receiver's "A" and "B" lines in order to match the data line characteristic
impedance and reduce signal reflection. This setting is useful when the
converter is installed at the end of a RS-485 or RS-422 bus.
If the internal 120 Ohm terminator is not appropriate for your application,
use [T-D] to disable it and use external one.
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SW1-4
TXC RS-485/422 driver enable control by RTS orADC
TXE RS-485/422 driver is forced to enable
[TXC] setting enables RS-485/422 driver to be controlled by RTS method
orADC method. RTS method is described later. Refer to SW2 settings for
more description aboutADC method.
[TXE] setting forces RS-485/422 driver to be enabled always. This setting
is applied when Master function is required in an RS-485/RS-422 multi-
drop bus.
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SW1-5
RTS-D
RTS-E
Disable RTS control for RS-485/422 driver
Enable RTS control for RS-485/422 driver
RTS control method allows the connected RS-232 device (such as a PC)
to control RTS signal (CTS input at the converter end) by software to
enable or disable RS-485/422 driver. [RTS-D] setting is used to disable
RTS control method.
SW1-6
RXC RS-485/422 receiver enable control by RTS orADC
RXE RS-485/422 receiver is forced to enable.
[RXC] setting enable to use the same [TXC] logic but reverse it as RXC
for the RS-485/422 receiver control. It means when the driver is enabled
the receiver is disabled. The receiver is enabled when the driver is dis-
abled. This setting is applied when a half-duplex communication is
adopted.
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SW1-8&7
BIAS-D RS-485/422 receiver line bias is disabled
BIAS-E RS-485/422 receiver line bias is enabled
The line bias is used to maintain the proper idle-state voltage to the idle
condition (when no driver is enabled on the bus). These bias resistors are
pull-up resistors on the data B line and pull-down resistors (to ground)
on dataAline. In 4-wire configuration, the bias resistors are placed on the
receiver lines. [BIAS-D] disables the internal BIAS resistors on receiver
lines.
[BIAS-E] setting enables internal bias resistors. The bias configuration
can support up to 30 receiver nodes with no terminators. If the bias
configuration is not proper for your physical topology, set to [BIAS-D]
and use external bias design according to your application.
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SW2-1
SDD DisableADC control for RS-485/422 driver
SDE EnableADC control for RS-485/422 driver
ADC method involves special circuitry that senses when data is received
on the RS-232 interface and is being transmitted and automatically en-
ables the RS-485/422 driver as well as disabling the driver within one
character length of the end of transmission. This is a useful method for
driver control since it needs no software involved.
In order to obtain an optimal performance, set SW2-2 ~ SW2-8 the asso-
ciated timing parameter for each RS-232 baud rate.
SW2-2 1200
SW2-3 2400
SW2-4 4800
SW2-5 9600
SW2-6 19200
SW2-7 38400
SW2-8 115200
ADC Timing parameter for RS-232 baud 1200
ADC Timing parameter for RS-232 baud 2400
ADC Timing parameter for RS-232 baud 4800
ADC Timing parameter for RS-232 baud 9600
ADC Timing parameter for RS-232 baud 19200
ADC Timing parameter for RS-232 baud 38400
ADC Timing parameter for RS-232 baud 115200
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2.7.1 RS-485/422 Driver and Receiver Control
The following table lists the possibleDIP SW settings related to RS-485
and RS-422 driver and receiver control:
SW1-4 SW1-6 SW1-5 SW2-1 Behavior
TXE
TXE
TXC
TXC
TXC
RXC
RXE
RXE
RXE
RXC
RTS-D
SDD
Driver is enabled.
Receiver is disabled.
-
-
Driver is enabled.
Receiver is enabled.
RTS-D
RTS-E
RTS-E
SDD
SDD
SDD
Driver is disabled.
Receiver is enabled.
Driver controlled by RTS
Receiver is enabled.
Driver controlled by RTS
Receiver is enabled
when driver is disabled.
TXC
TXC
RXE
RXC
RTS-D
RTS-D
SDE
SDE
Driver controlled byADC
Receiver is enabled.
Driver controlled byADC
Receiver is enabled
when driver is disabled.
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2.8 Making Serial RS-232 Connection
Typical RS-232 InterfaceDCE PinAssignment Table
Pin#
Signal Name
Received Line Signal Detect
TX Data
RX Data
DTE Ready
Signal Ground
DCE Ready
Clear To Send
Request To Send
Ring Indicator
Input/Output
Output
Output
Input
1
2
3
4
5
6
7
8
9
Input
Output
Output
Input
Output
Output
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The RS-232 to RS-485/422 converter as an interface between an RS-232
device and RS-485 or RS-422 bus. The connection is illustrated as fol-
lows:
The following signals received on the RS-232 interface are converted to
RS-485 bus signals:
Pin#
SignalName
TXData
RXData
Input/Output
Output
Input
2
3
7
Clear To Send
Input
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2.8.1 Cable for Connection to PC COM Port
Connecting to 9-pinDTE device (Computer or PC COM)
Connecting to 25-pinDTE device (Computer or PC COM)
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3 Making RS-485/422 Connection
EIA-485 [TIA-485] Balanced (differential) interface; defines the Physical
layer, signaling protocol is not defined. EIA-485 specifies bidirectional,
half-duplex data transmission. Up to 32 transmitters and 32 receivers may
be interconnected in any combination, including one driver and multiple
receivers (multi-drop), or one receiver and multiple drivers.
EIA/TIA-422 define a Balanced (differential) interface; specifying a single,
unidirectional driver with multiple receivers (up to 32). RS-422 will sup-
port Point-to-Point, Multi-Drop topology, but not Multi-Point [EIA485].
EIA-485 devices may be used in 422 circuits, but EIA-422 may not be
used in 485 circuits (because of the lack of an Enable line).
The published TIA/EIA485 and RS-422 standards define only the electri-
cal characteristics of the drivers and receivers as listed below. They did
not standardize such things such as cables and connectors, pinouts, bus
arbitration, signaling protocols, or physical wiring topology. Many dif-
ferent implementations have come into use and they are often incompat-
ible with each other.
Characteristics
RS-422
RS-485
Mode of operation
Differential
Unidirectional
Multipoint
1 Tx, 10 Rx
4000ft length
10Mbps
Differential
FullDuplex
Multipoint
32 Tx, 32 Rx
4000ft length
10Mbps
+/- 1.5V
Allowed no. of Tx and Rx
Maximum cable length
Maximum data rate
Minimum Tx driver output range +/- 2V
Maximum Tx driver output range +/- 5V
Maximum Tx short-circuit current 150mA
+/- 5V
250mA
Tx load impedance
Rx input sensitivity
Maximum Rx input resistance
Rx input voltage range
Rx logic high
100
+/- 200mV
4k
+/- 7V
>200mV
<200mV
54
+/- 200mV
12k
-7V to +12V
>200mV
<200mV
Rx logic low
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RS-485 and RS-422 are in wide use as an interface for telecommunica-
tions, industrial, medical, security and networking applications. The fol-
lowing sections describe examples of some of popular physical
topologies.
3.1 RS-422 Point-to-Point Circuit
This is the simplest configuration, just one driver and one receiver. If
termination is used, it is only required at the receiver. Most RS-422 cables
used to connect telecom or data-com equipment are point to point links.
The converter can convert an RS-232 device into a Driver node in this
point-to-point circuit.
The configuration is:
SW1-4
SW1-6
SW1-5
SW2-1
TXE
EnableDriver always
Enable Receiver RTS/ADC Control
Disable RTS control
RXC
RTS-D
SDD
DisableADC control
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It also can convert an RS-232 device into a receiver node in this point-to-
point circuit.
The configuration for a RECEIVER node is:
SW1-4
SW1-6
SW1-5
SW2-1
TXC
RXE
RTS-D
SDD
Enable RTS/ADC Control forDriver
Enable Receiver always
Disable RTS control
DisableADC control
3.2 RS-422 Multi-drop Network
In this topology there is only one driver sending to one or more receiv-
ers. One termination resistor is recommended at the extreme end of the
bus to eliminate reflections. Up to 10 receivers are permitted under RS-
422. Multiple receive-only nodes may be used for point-to-multipoint
communications.
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The converter can convert an RS-232 device into a Master node in this
multi-drop network.
The configuration for MASTER node is:
SW1-4
SW1-6
SW1-5
SW2-1
TXE
EnableDriver always
Enable Receiver RTS/ADC Control
Disable RTS control
RXC
RTS-D
SDD
DisableADC control
It also can convert an RS-232 device into a SLAVE node in this multi-drop
network.
The configuration for a SLAVE node is:
SW1-4
SW1-6
SW1-5
SW2-1
TXC
RXE
RTS-D
SDD
Enable RTS/ADC Control forDriver
Enable Receiver always
Disable RTS control
DisableADC control
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3.3 RS-485 Multi-drop Network
This topology is similar to RS-422 multi-drop. However, up to 32 receiv-
ers are permitted under RS-485. This may be used for point-to-multipoint
communications.
The converter can convert an RS-232 device into a Master node in this
multi-drop network as illustrated below:
The configuration for MASTER node is:
SW1-4
SW1-6
SW1-5
SW2-1
TXE
EnableDriver always
Enable Receiver RTS/ADC Control
Disable RTS control
RXC
RTS-D
SDD
DisableADC control
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It is also able to convert an RS-232 device into a SLAVE node in this multi-
drop network.
The configuration for a SLAVE node is:
SW1-4
SW1-6
SW1-5
SW2-1
TXC
RXE
RTS-D
SDD
Enable RTS/ADC Control forDriver
Enable Receiver always
Disable RTS control
DisableADC control
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3.4 RS-485 Half-duplex 2-wire Network
This is the typical RS-485 topology. It takes advantage of RS-485 capabil-
ity to support multiple drivers on a bus. RS-422 devices should not be
used in this configuration. This topology enables bidirectional communi-
cation from many nodes over long distances at low to medium data rates,
all on a single pair of wires (2-wire).
It can implement a very functional, very flexible and very economical data
network. Because signals travel in both directions, this bus should be
terminated at both ends to prevent reflections. Only one node can drive
the bus at a time, making this a half-duplex communication channel. Only
one driver should be active at any one time. Therefore the transceivers
used on a half-duplex bus should support a Driver Enable function.
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The converter features RS-485 driver and receiver in one device. It also
provides very flexible configuration settings for Driver Enable control
and Receiver Enable control. The configuration for the node in RS-485 2-
wire network is:
SW1-2&1 2W
Select 2-wire topology
SW1-4
SW1-6
SW1-5
SW2-1
TXC
RXC
RTS-E
SDE
Enable RTS/ADC Control forDriver
Enable RTS/ADC Control for Receiver
Use RTS control (optional)
UseADC control (optional)
SW2-2-8 Baud
SW1-3 T-D
Baud whenADC control is enabled (optional)
Disable internal terminator (optional)
3.5 RS-485 Full-duplex 4-wire Network
The 4-wire network simplifies bus arbitration in multi-node RS-485. A
single Master node is the only driver allowed on the top most wire pair.
All other nodes listen to all data traffic that passes on the party-line type
multi-drop bus. Nodes may transmit on the lower pair of wires when
addressed by the master node or by using a software token-passing bus
arbitration scheme.
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The master node may drive its bus while any of the slave nodes are
driving the lower pair, making this 4-wire network a full-duplex communi-
cation channel. All communication occurs from master to slave or slave
to master, so any peer to peer communications must be routed through
the master node.
To convert an RS-232 device into a Master node in RS-485 4-wire net-
work, the configuration is:
SW1-2&1 4W
Select 4-wire topology
SW1-4
SW1-6
SW1-5
SW2-1
SW2-2-8 Baud
SW1-3 T-D
TXE
RXC
RTS-E
SDE
EnableDriver always
Enable RTS/ADC Control for Receiver
Use RTS control (optional)
Or useADC control (optional)
Baud when ADC control is enabled (optional)
Disable internal terminator (optional)
To convert an RS-232 device into a Slave node in RS-485 4-wire network,
the configuration is:
SW1-2&1 4W
Select 4-wire topology
SW1-4
SW1-6
SW1-5
SW2-1
SW2-2-8 Baud
SW1-3 T-D
TXC
RXE
RTS-E
SDE
Enable RTS/ADC Control forDriver
Enable Receiver always
Use RTS control (optional)
Or useADC control (optional)
Baud when ADC control is enabled (optional)
Disable internal terminator (optional)
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3.6 Summary of the Converter Applications
The common topologies implemented with RS-485 and RS-422 are:
1. RS-422 point to point in 2 -wire circuit
2. RS-422 2-wire multi-drop network
3. RS-485 2-wire multi-drop network
4. RS-485 half-duplex bidirectional network in 2-wire topology
5. RS-485 full-duplex bidirectional network in 4-wire topology
The converter is equipped with functionality and flexibility to convert an
RS-232 device to a node in any one of the above topologies.
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4 LED Indicators
The following figure shows the locations of the LED indicators:
4.1 LED Indicators
LED
DISPLAY
STATE INTERPRETATION
PWR
Power status
ON
OFF
The device is powered on.
The device is powered off.
232 TX RS-232 TX
232RX RS-232RX
ON
OFF
RS-232 TX data is present
No RS-232 TX data
ON
OFF
RS-232 RX data is present
No RS-232 RX data
TXC
RS-485
ON
The driver is enabled.
Driver Enable
OFF
The driver is disabled and
is in tri-state (high-impedance).
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5 Factory Default Configuration
The following table lists the factory default settings for configuration
DIPSW:
SW
Name
Default Setting
SW1-2&1 4W
4-wire (RS-485/422 driver receiver separated)
SW1-3
SW1-4
SW1-5
SW1-6
T-D(Off)
TXC (Off)
Disable RS-485/422 receiver terminator
RS-485/422 driver enable control by RTS orADC
RTS-D (Off) Disable RTS control for RS-485/422 driver
RXC(Off) RS-485/422receiverenablecontrolbyRTSorADC
SW1-8&7 BIAS-D (Off) Disable RS-485/422 line bias
SW2-1
SW2-2
SW2-3
SW2-4
SW2-5
SW2-6
SW2-7
SW2-8
SDE (On)
Off
EnableADC control for RS-485/422 driver
DisableADC Timing for RS-232 baud 1200
DisableADC Timing for RS-232 baud 2400
DisableADC Timing for RS-232 baud 4800
SelectADC Timing for RS-232 baud 9600
DisableADC Timing for RS-232 baud 19200
DisableADC Timing for RS-232 baud 38400
DisableADC Timing for RS-232 baud 115200
Off
Off
9600 (On)
Off
Off
Off
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