Delta MH300 Series - A-3 Communication Protocol

Appendix A. Modbus Protocol
MS300
A-4
A-3 Communication Protocol
1. Communication data frame
ASCII mode:
STX
Start character = ‘:’ (3AH)
Address High
Communication address:
one 8-bit address consists of 2 ASCII codes
Address Low
Function High
Command code:
one 8-bit command consists of 2 ASCII codes
Function Low
DATA (n-1)
Contents of data:
n x 8-bit data consists of 2n ASCII codes
n ≤ 16, maximum of 32 ASCII codes (20 sets of data)
…….
DATA 0
LRC Check High
LRC checksum:
one 8-bit checksum consists of 2 ASCII codes
LRC Check Low
END High
End characters:
END Hi = CR (0DH), END Lo = LF(0AH)
END Low
RTU
mode:
START
Defined by a silent interval of larger than / equal to 3.5 char
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 3.5 char
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
3. Functi
on (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.