Lrc And Crc Transmission Error Check - Delta ASDA-A3 Series User Manual

ASDA-A3

LRC and CRC transmission error check

The error check in ASCII mode is LRC (Longitudinal Redundancy Check). In RTU mode, it is
CRC (Cyclical Redundancy Check). See the details below.
LRC (ASCII mode):
To calculate the LRC: 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.
Revision December, 2017
Start
Slave Address
Function
Start Data Address
Data Number
LRC Check
End 1
End 0
MODBUS Communication
':'
'7'
'F'
'0'
'3'
'0'
'5'
'C'
'4'
'0'
'0'
'0'
'1'
'B'
'4'
(0DH) (CR)
(0AH) (LF)
9
9-11