Advantech Data Acquisition Modules ADAM 4000 Manuel d'utilisateur télécharger pdf (Page 413)

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Appendix F

Appendix F How to use the Checksum feature F

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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.

1 2 ... 408 409 410 411 412 413 414 415 416 417 418 ... 428 429

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