Diagnostics (Function Diagnostics: 08H) - Mitsubishi Electric MR-JE-C Series Instruction Manual

4. Modbus RTU
The following shows the information in each Response Message.
Message
Slave Address
Function
Byte Count
Data
CRC Check

4.8.3 Diagnostics (Function diagnostics: 08h)

Use this register when performing the communication check from the master (controller). When a slave
(servo amplifier) received a Query Message, the slave sends the received data as a Response Message
without any changes to the master (controller).
(1) Message frame
Query Message
Slave Address Function
(8 bits) 08h
Message
Slave Address
Function
Sub Function
Data
CRC Check
Response Message
Slave Address Function
(8 bits) 08h
Message
Slave Address
Function
Sub Function
Data
CRC Check
The station number "02h" is returned.
The value "03h" is returned. This means that the message was received without errors.
The value "08h" is returned. This means that data of 8 frames is returned.
Data starting from the start address is returned.
Lower-bit value of the register 2B05h: "5678h"
Higher-bit value of the register 2B05h: "1234h"
Value of the register 2B06h: "1000h"
Value of the register 2B07h: "2000h"
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 servo amplifier, and the result of the calculation is
returned.
Sub Function
H L
00h 00h
Size
Set a station number to which the message is sent.
8 bits
The number "0" (station number for broadcast sending) cannot be set.
8 bits Set "08h".
Set "0000h".
16 bits
When a value other than "0000h" is set, a communication error occurs.
16 bits Set 2-byte length data.
Data for CRC error check
16 bits
This data is calculated automatically by a controller.
Sub Function
H L
00h 00h
Size
8 bits The station number of a slave (servo amplifier) is returned.
8 bits When the Query Message was received without errors, "08h" is returned.
16 bits The value "0000h" is returned.
16 bits The data set in the Query Message is returned.
Data for CRC error check
16 bits
This data is calculated automatically by a servo amplifier, and the result of the
calculation is returned.
4 - 8
Description
Data
H L
(8 bits) (8 bits)
Description
Data
H L
(8 bits) (8 bits)
Description
CRC Check
L H
(8 bits) (8 bits)
CRC Check
L H
(8 bits) (8 bits)