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7 Using Modbus-RTU Slave Mode
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
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Command and Response Details
The Modbus-RTU Slave Mode of the Serial Communications Unit supports the following Modbus-RTU
commands.
The frame format used in Modbus-RTU Slave Mode is as follows:
* The CRC code is given in the order of low byte to high byte.
Additional Information
•
Set the slave address to 0 for a broadcast command. Responses are not returned for broad-
cast commands.
•
Modbus data models are allocated to the memory used for CJ-series Unit by the System Set-
tings. System settings are read when the Controller is reset, when the Serial Communications
Unit is restarted, or when the port is restarted.
Precautions for Correct Use
Precautions for Correct Use
Create a program for retry processing on the host computer (e.g. personal computer) for a trans-
mission error or other communications errors.
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Supported Modbus-RTU Commands
Function code
(hexadecimal)
Function
Modbus name
01
Reads multiple bits from the CIO, Work,
Holding, or Auxiliary Area of the memory
used for CJ-series Unit
Read Coils
02
Reads multiple bits from the CIO Area of
the memory used for CJ-series Unit
Read Discrete Inputs
03
Reads multiple words from the DM or
EM Area of the memory used for CJ-
series Unit
Read Holding Registers
04
Reads multiple words from the CIO,
Work, Holding, or Auxiliary Area of the
memory used for CJ-series Unit
Read Input Registers
05
Writes a bit in the memory used for CJ-
series Unit
Write Single Coil
06
Writes a word in the DM or EM Area of
the memory used for CJ-series Unit.
Write Single Register
08
Executes an echoback test.
Diagnostic
0F
Writes multiple bits in the memory used
for CJ-series Unit
Write Multiple Coils
10
Writes multiple words in the DM or EM
Area of the memory used for CJ-series
Unit
Write Multiple Registers
Slave address
Function code
Data
CRC
1 byte
1 byte
0 to 252 bytes
2 bytes (*)
Содержание CJ1W-SCU22
Страница 192: ...4 Using Protocol Macros 4 56 CJ series Serial Communications Units Operation Manual for NJ series CPU Unit W494...
Страница 250: ...6 No protocol Mode 6 22 CJ series Serial Communications Units Operation Manual for NJ series CPU Unit W494...
Страница 460: ...A Standard System Protocol R 126 CJ series Serial Communications Units Operation Manual for NJ series CPU Unit W494...
Страница 473: ...Index 1 CJ series Serial Communications Units Operation Manual for NJ series CPU Unit W494 I Index...