REXROTH EFC 3600 - Page 203

Function example
Function 0x03: Read N register words, range: 1 ~ 16
Example: It is necessary to read 2 continuous words starting from communica-
tion register 0100H of the slave frequency converter addressed at 01H. The
frame structure is described in the tables below.
Message start Transmission time for 3.5 bytes
Slave address 01H
ModBus function code 03H
Higher byte of start address 01H
Lower byte of start address 00H
Higher byte of data 00H
Lower byte of data 02H
CRC lower byte C5H
CRC higher byte F7H
Message end Transmission time for 3.5 bytes
Tab. 13-13: Function 0x03_Request from RTU master
Message start Transmission time for 3.5 bytes
Slave address 01H
ModBus function code 03H
Bytes of data 04H
Higher byte of data in register 0100H 00H
Lower byte of data in register 0100H 05H
Higher byte of data in register 0101H 00H
Lower byte of data in register 0101H 00H
CRC lower byte EAH
CRC higher byte 32H
Message end Transmission time for 3.5 bytes
Tab. 13-14: Function 0x03_Response from RTU slave
EFC 3600 Bosch Rexroth AG
Communication Protocols
DOK-RCON03-EFC-3600***-IT03-EN-P
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