Appendix A. Modbus ProtocolC2000 Plus
A-5
RTU mode:
Command Message Response Message
Address 01H Address 01H
Function 03H Function 03H
Starting data register
21H
Number of register
(count by byte)
04H
02H
Number of register
(count by word)
00H Content of register
address 2102H
17H
02H 70H
CRC Check Low 6FH Content of register
address 2103H
00H
CRC Check High F7H 00H
CRC Check Low FEH
CRC Check High 5CH
3. 06H: single write, write single data to a register.
Example: Writing data 6000 (1770H) to register 0100H. AMD address is 01H.
ASCII mode:
Command Message Response Message
STX ‘:’ STX ‘:’
Address
‘0’
Address
‘0’
‘1’ ‘1’
Function
‘0’
Function
‘0’
‘6’ ‘6’
Target register
‘0’
Target register
‘0’
‘1’ ‘1’
‘0’ ‘0’
‘0’ ‘0’
Register content
‘1’
Register content
‘1’
‘7’ ‘7’
‘7’ ‘7’
‘0’ ‘0’
LRC Check
‘7’
LRC Check
‘7’
‘1’ ‘1’
END
CR
END
CR
LF LF
RTU mode:
Command Message Response Message
Address 01H Address 01H
Function 06H Function 06H
Target register
01H
Target register
01H
00H 00H
Register content
17H
Register content
17H
70H 70H
CRC Check Low
CRC Check High
86H
CRC Check Low
CRC Check High
86H
22H 22H