Vaisala PTB220 User Manual download pdf (Page 105)

APPENDIX I ________________________________________________________________ CHECKSUM

VAISALA _________________________________________________________________________ 99

APPENDIX I CHECKSUM

With a CHECKSUM form the user can check that the data sent by the

barometer has not changed in transfer line. The CHECKSUM format can

be output with 4 (CS4) or 2 (CS2) hex numbers. The PTB220

calculates the checksum value of all the numbers set before the

parameter CS4/CS2.

>form<cr>

4.2P""CS4#r#n

>send<cr>

994.16 017B

(Please note, there is a space between P and " "-marks)

In following there is an example of checksum calculation of number

1010.09.

1 31 hex

0 30 hex

1 31 hex

0 30 hex

. 2E hex

0 30 hex

9 39 hex

20 hex (space)

179 hex (sum of hex values)

CS4 0179

CS2 79

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 111 112 113

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Vaisala PTB220 User Manual Page 105