Delta ASDA-A3 Series User Manual page 874

ASDA-A3
LRC and CRC transmission error checking
In ASCII mode, the error checking method is LRC (Longitudinal Redundancy Check). In RTU
mode, the error checking method is CRC (Cyclical Redundancy Check). See the following
details.
LRC (ASCII mode):
To calculate the LRC value: add all the bytes, round down the carry, and take the two's
complement. For example: 7FH + 03H + 05H + C4H + 00H + 01H = 14CH, round down the
carry 1 and take 4CH. The two's complement of 4CH is B4H.
Start
Slave Address
Function
Start Data Address
Data Quantity
(in words)
LRC
End 1
End 0
Modbus Communication
':'
'7'
'F'
'0'
'3'
'0'
'5'
'C'
'4'
'0'
'0'
'0'
'1'
'B'
'4'
(0DH) (CR)
(0AH) (LF)
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