Appendix A. Modbus ProtocolC2000 Plus
A-4
RTU mode:
START Defined by a silent interval of larger than / equal to 10 ms
Address Communication address: 8-bit binary address
Function Command code: 8-bit binary command
DATA (n-1)
Contents of data:
N × 8-bit data, n ≤ 16
…….
DATA 0
CRC Check Low CRC checksum:
one 16-bit CRC checksum consists of 2 8-bit binary
characters
CRC Check High
END Defined by a silent interval of larger than / equal to 10 ms
2. Communication address (Address)
00H: broadcast to all AC motor drives
01H: AC motor drive of address 01
0FH: AC motor drive of address 15
10H: AC motor drive of address 16
:
FEH: AC motor drive of address 254
Function (function code) and data (data characters)
03H: read data from a register
Example: Reading two continuous data from register address 2102H, AMD address is 01H.
ASCII mode:
Command Message Response Message
STX ‘:’ STX ‘:’
Address
‘0’
Address
‘0’
‘1’ ‘1’
Function
‘0’
Function
‘0’
‘3’ ‘3’
Starting register
‘2’
Number of register
(count by byte)
‘0’
‘1’ ‘4’
‘0’
Content of starting
register 2102H
‘1’
‘2’ ‘7’
Number of register
(count by word)
‘0’ ‘7’
‘0’ ‘0’
‘0’
Content of register 2103H
‘0’
‘2’ ‘0’
LRC Check
‘D’ ‘0’
‘7’ ‘0’
END
CR
LRC Check
‘7’
LF ‘1’
END
CR
LF