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Appendix B. Modbus ProtocolEB3000
B-4-3 Function (Function Code) and DATA (Data Characters)
1. 03H: read data from a register
Example: Reading two continuous data from register address 2102H, AMD address is 01H.
ASCII mode:
Command Message
STX
Address
Function
Starting register
Number of register
(count by word)
LRC Check
END
RTU mode:
Command Message
Address
Function
Starting data register
Number of register
(count by word)
CRC Check Low
CRC Check High
':'
'0'
'1'
'0'
'3'
'2'
Number of register
'1'
(count by byte)
'0'
'2'
Content of starting
'0'
register 2102H
'0'
'0'
'2'
Content of register 2103H
'D'
'7'
CR
LRC Check
LF
01H
03H
21H
Number of register
02H
(count by byte)
00H
Content of register
02H
address 2102H
6FH
Content of register
F7H
address 2103H
CRC Check Low
CRC Check High
B-6
Response Message
STX
Address
Function
END
Response Message
Address
Function
':'
'0'
'1'
'0'
'3'
'0'
'4'
'1'
'7'
'7'
'0'
'0'
'0'
'0'
'0'
'7'
'1'
CR
LF
01H
03H
04H
17H
70H
00H
00H
FEH
5CH
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