Danfoss VLT MICRO Manual page 95

3.6 Chk (check sum)
Check Sum is calculated by summing up ADR to ET. For Example, reading address
01 as Pr.04 of AC drive.
ADR ADR
STX
1 0
30H 31H
02H
"0" "1"
30H + 31H + 30H + 38H + 30H + 34H + 03H = 130H
ASCII mode: ASCII mode: ASCII mode:
ASCII mode: ASCII mode:
LRC (Longitudinal Redundancy Check) is calculated by summing up, module 256, the values
of the bytes from ADR1 to last data character then calculating the hexadecimal representation
of the 2's-complement negation of the sum.
For example, reading 1 word from address 0401H of the AC drive with address 01H
STX
ADR 1
ADR 0
CMD 1
CMD 0
Starting data
address
Number of data
LRC CHK 1
LRC CHK 0
END 1
END 0
CMD CMD 0
1 0
30H 38H
"0" "8"
':'
'0'
'1'
'0'
'3'
'0'
'4'
'0'
'1'
'0'
'0'
'0'
'1'
'F'
'6'
CR
LF
95
VLT
......
1 N-1 N
30H , 34H
"0" , "4"
01H+03H+04H+01H+00H+01H=0AH,
the 2's-complement negation of
0AH is F6H.
® ® ® ® ®
MICRO
ETX CHK CHK
1 0
03H 33H 30H
"3" "0"