301
Modbus-RTU Slave Function for Replacing Existing PLCs Section 9-6
Modbus-RTU Slave Compatible Device Modes
Note 1. The response data formats for MS commands when FAL/FALS is not exe-
cuted are as follows:
Types for which a space (20 hex) is added to the FAL/FALS message in the
response data (indicated as fixed length in the above table).
Types for which a FAL/FALS message is not added to the response data
(indicated as variable length in the above table).
(A FAL/FALS message is added to the response data for both types if FAL/
FALS is executed.)
2. The following condition is an exception:
When reusing the RG command created using a CVM1/CV-series PLC
with mode B selected, the host computer program cannot be reused with-
out being changed. The difference in the response returned when the RG
command is reused and the Timer/Counter Flag for 121 words (maximum
text area) is read is as follows:
Modbus-
RTU Slave-
compatible
device mode
Compatible models (models that sup-
ported host computer programs)
RR, RL, RH, RC, RD,
and RJ commands
RG command MS command
(See note.)
Number of words in each response frame Response data
format
First frame Second
frame
First frame Second
frame
Mode A (CS/
CJ/C)
C Series
SRM1 (built-in port)
CPM1 (built-in port)
CPM1A (built-in port)
CQM1-CPU
@@ (built-in port)
C200HS-CPU
@@ (built-in port)
C200HE/HG/HX-CPU
@@ (built-in port)
C200HW-COM
@@ (built-in port)
CS/CJ Series
CS1G/H-CPU
@@H (built-in port)
CS1G/H-CPU
@@-V1 (built-in port)
CS1D-CPU
@@H (built-in port)
CJ1G/H-CPU
@@H (built-in port)
CJ1G/M-CPU
@@ (built-in port)
Earlier models (pre-Ver. 1.2):
CS1W-SCB21(-V1)/41(-V1)
CS1W-SCU21(-V1)
CJ1W-SCU21/41
30 words 31 words 121 words 125 words Variable length
Mode B
(CVM1/CV)
CVM1/CV Series
CVM1/CV-CPU
@@ CVM1 (built-in
port), CV500-LK201
Fixed length
Mode C
(C200H)
C Series (C200H)
C200H-LK101/201/202
29 words 30 words 89 words 89 words Variable length
Mode D
(C500/120)
C Series (C500/120)
C500-LK101/201/103/203, C120-
LK101/201/202
89 words 60 words
Using mode B with a CS/CJ-series
Serial Communications Unit/Board
with unit version 1.2 or later
First frame
121 words (including terminator)
First frame
121 words
Second frame
0 words (terminator only)
CVM1/CV-series Host Link Unit
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