7. MODBUS
IMS01J02-E4
113
7.2.3 Diagnostics (Loopback test) [08H]
The master’s query message will be returned as the response message from the slave.
This function checks the communication system between the master and slave (SR Mini HG SYSTEM
control unit).
Example: Loopback test for slave address 1
Query message
Slave address
01H
Function code
08H
Test code
High
00H
Low
00H
Data High
1FH
Low
34H
CRC-16 High
E9H
Low
ECH
Normal response message
Slave address
01H
Function code
08H
Test code
High
00H
Low
00H
Data High
1FH
Low
34H
CRC-16 High
E9H
Low
ECH
Error response message
Slave address
01H
80H
Function code
88H
Error code
03H
CRC-16 High
06H
Low
01H
Test code must be set to “00”
Contents will be the same as query message data
Any pertinent data