Advantech Data Acquisition Modules ADAM 4000 - Manual (Page 413)

Appendix F
Appendix F How to use the Checksum feature F-3
Example 2
This example explains how to calculate the checksum value of a Read
High alarm limit command string:
Case 1. (If the Checksum feature is disabled)
Command: $07RH(cr)
Response: !07+2.0500(cr) when the command is valid.
Case 2. (If the Checksum feature is enabled)
Command: $07RH25(cr)
Response: !07+2.0500D8(cr)
where:
25 represents the checksum of this command, and
D8 represents the checksum of the response.
The checksum of the command string is derived as shown below:
25h = (24h+ 30h + 37h + 52h + 48h) MOD 100h
The hexadecimal ASCII codes for $, 0, 7, R, H are 24h, 30h, 37h, 52h
and 48h respectively. The sum of these ASCII codes is 125h, and the
result equals to 25h after modulus-256(100h) execution.