REXROTH EFC 3600 - Page 205

Function 0x08: Diagnostics
Example: To test the communication loop of 2 continuous words 1234H and
5678H with frequency converter slave address 01H, the frame structure is de-
scribed in the tables below:
Message start Transmission time for 3.5 bytes
Slave address 01H
ModBus function code 08H
Higher byte of sub-function 00H
Lower byte of sub-function 00H
Higher byte of test word 1 12H
Lower byte of test word 1 34H
Higher byte of test word 2 56H
Lower byte of test word 2 78H
CRC lower byte 73H
CRC higher byte 33H
Message end Transmission time for 3.5 bytes
Tab. 13-17: Function 0x08_Request from RTU master
Message start Transmission time for 3.5 bytes
Slave address 01H
ModBus function code 08H
Higher byte of sub-function 00H
Lower byte of sub-function 00H
Higher byte of test word 1 12H
Lower byte of test word 1 34H
Higher byte of test word 2 56H
Lower byte of test word 2 78H
CRC lower byte 73H
CRC higher byte 33H
Message end Transmission time for 3.5 bytes
Tab. 13-18: Function 0x08_Response from RTU slave
EFC 3600 Bosch Rexroth AG
Communication Protocols
DOK-RCON03-EFC-3600***-IT03-EN-P
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