Mitsubishi Electric MR-JE-C Series Instruction Manual page 56

4. Modbus RTU
(2) Usage example
The following shows a setting example for writing "0100h" in the Modbus register 2102h ([Pr. PC02]) of
the slave address "02h".
Index Name
2102h PC02
Query Message
Starting Address
Slave
Function
Address
H
02h 10h 21h
Set the following values to each Query Message.
Message
Slave Address
Function
Starting Address
No. of Registers
Byte Count
Data
CRC Check
Response Message
Slave Address Function
02h 10h
The following shows the information in each Response Message.
Message
Slave Address
Function
Starting Address
No. of Registers
CRC Check
Data type Access
U32 rw
No. of Registers
Byte
Count
L H L
02h 00h 02h
Set the station number "02h".
Set "10h".
Set "2102h", the start address of the registers to which data is written.
Set "02h", because the total number of write points of the Modbus register 2102h is 2.
Set "04h". This means that data of 4 frames is sent.
Set values in order starting from the start address.
Lower-bit value of the register 2102h: "0100h"
Higher-bit value of the register 2102h: "0000h"
The endian setting of 4-byte data can be selected with "Modbus RTU communication endian
selection" of [Pr. PC72 Function selection C-G]. This example shows the case when the standard
endian (initial value) is set.
Data for CRC error check
This data is calculated automatically by a controller.
Starting Address
H L
21h 02h
The station number "02h" is returned.
The value "10h" is returned. This means that the message was received without errors.
The value "2102h", the start address of the holding registers to which the data was written is
returned.
H: "21h"
L: "02h"
The number of registers to write "02h" is returned.
Data for CRC error check
This data is calculated automatically by a servo amplifier, and the result of the calculation is
returned.
No. of Registers
2
Data
H L
04h 01h 00h
Description
No. of Registers
H
00h
Description
4 - 11
Continuous
Setting value
read/write
CRC Check
H L L
00h 00h
(8 bits) (8 bits)
CRC Check
L L
02h (8 bits)
00000100h
H
H
(8 bits)