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Section 1-3
Protocol Overview
Note
1-3
*The CS-series Serial Communications Boards/Units without the “-V1” suffix
do not support this Simple Backup Function, but the CJ1W-SCU21/41 does
support this function even though the model number lacks the “-V1” suffix.
Protocol Overview
A Serial Communications Board is an Inner Board for CS-series CPU Units
that provides RS-232C and/or RS-422A/485 serial ports. An Inner Board is an
option and is installed in the CPU Unit.
A Serial Communications Unit is a CPU Bus Unit that provides two RS-232C
serial ports or one RS-232C and one RS-422A/485 port. The following eight
serial communications modes can be used as required for each serial port.
• Host Link:
For connections between host computers and PLCs
• Protocol macro: For communications between PLCs and general-purpose
external devices
• 1:N NT Link:
For communications between PLCs and Programmable
Terminals (PTs)
• Loopback test: For testing the communications ports
• Serial Gateway
• No-protocol
• 1:1 Host Link
• Modbus-RTU slave mode
Note
(1) The Serial Gateway can also be executed in protocol macro mode.
(2) Modbus-ASCII mode is not supported.
PLC
Series
CS
CJ
Product
Serial
Communications
Boards
Model
number
Serial communications mode
Host Link
Protocol
macro
1:N NT Link
(See note 2.)
Loopback
test
Serial
Gateway
Serial
Gateway in
protocol
macro
mode
Noprotocol
(See
note
3.)
1:1
Host
Link
ModbusRTU
slave
CS1WSCB21-V1
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
CS1WSCB41-V1
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
Serial
CS1WCommuniSCU21-V1
cations Unit
CS1WSCU31-V1
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
RS-232C
OK
Serial
CJ1WCommuniSCU21-V1
cations Unit
CJ1WSCU31-V1
CJ1WSCU41-V1
---
Serial ports
OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
RS-232C
OK
OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
RS-422A/485 OK (See note 1.) OK
OK
OK
OK
OK
OK
OK
OK
RS-232C
OK
OK
OK
OK
Generalpurpose
external
device
Host Link computer
Device to be connected
Supporting unit versions
OK
OK
OK
OK
OK
Host computer
or Programming
Device
Generalpurpose
external
device
PT
None
Depends on the
protocol used at
the conversion
destination
All unit versions
Note
Unit version 1.2 or later
Unit version 1.3
or later
1. A 4-wire connection must be used when using Host Link communications
for an RS-422A/485 connector.
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