Delta ASD-B2-0121-F, User Manual

Page: 196 / 291

ASDA-B2-F Communications
September, 2015
8-11
8
LRC and CRC Transmission Error Check
The error check of ASCII mode is LRC (Longitudinal Redundancy Check) and CRC (Cyclical
Redundancy Check) is for RTU mode.
LRC (ASCII Mode):
The calculation of LRC is to add up all the byte, round down the carry and take 2’s complement.
For example: 7FH + 03H + 05H + C4H + 00H + 01H = 14CH, round down carry 1 and take 4CH.
2’s complement of 4CH is B4H.
Start ‘ : ’
Slave Address
‘7’
‘F’
Function
‘0’
‘3’
Start Data Address
‘0’
‘5’
‘C’
‘4’
Data Number
‘0’
‘0’
‘0’
‘1’
LRC Check
‘B’
‘4’
End 1 (0DH)(CR)
End 0 (0AH)(LF)