Bosch Rexroth EFC 3600 Operating Instructions Manual page 179

DOK-RCON03-EFC-3600***-IT01-EN-P
Rexroth Frequency Converter EFC 3600
ModBus function code
Higher byte of write register address
Lower byte of write register address
Higher byte of write data
Lower byte of write data
CRC lower byte
CRC higher byte
End
Fig.13-14: Function 0x06_Request from RTU master
Start
Slave address
ModBus function code
Higher byte of write register address
Lower byte of write register address
Higher byte of write data
Lower byte of write data
CRC lower byte
CRC higher byte
End
Fig.13-15: Function 0x06_Response from RTU slave
● 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 described in the
tables below:
Start
Slave address
ModBus function code
Higher byte of sub-function
Lower byte of sub-function
Higher byte of test word 1
Lower byte of test word 1
Higher byte of test word 2
Lower byte of test word 2
CRC lower byte
Communication Protocols
06H
00H
05H
00H
00H
99H
CBH
Transmission time for 3.5 bytes
Transmission time for 3.5 bytes
01H
06H
00H
05H
00H
00H
99H
CBH
Transmission time for 3.5 bytes
Transmission time for 3.5 bytes
01H
08H
00H
00H
12H
34H
56H
78H
73H
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