ICP DAS USA DGW-521 User Manual page 23

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Checksum Calculation:
1. Calculate the ASCII code sum of all the characters in the
command/response string except for the carriage return
character (CR).
2. The checksum is equal to the sum masked by 0ffh.
Example:
Command string: $012(CR)
1. Sum of the string = "$"+"0"+"1"+"2" = 24h+30h+31h+32h
= B7h
2. Therefore the checksum is B7h, and so
CHKSUM = "B7"
3. The command string with the checksum = $012B7(CR)
Response string: !01200600(CR)
1. Sum of the string =
"!"+"0"+"1"+"2"+"0"+"0"+"6"+"0"+"0" =
21h+30h+31h+32h+30h+30h+36h+30h+30h = 1AAh
2. Therefore the checksum is AAh, and so
CHKSUM = "AA"
3. The response string with the checksum = !01200600AA(CR)
Note:
All characters should be in upper case.
DGW-521 User Manual, Rev. A1.0 23