Checksum in datafeed

[Etienne]

The manual states

Start Char:50
Width: 2
Description: Checksum
Notes:The ascii-hex 2 byte sum of all 49 preceding bytes.

I have a question... Adding up 49 values with a range of 0..255 will probably result in a fairly large number, in the range 0..12,495. Since there are only 2 hex characters representing the checksum in the feed, this equates to a checksum range of 0..255.

So is the checksum the lower byte of an integer addition, or are the last 4 characters before the <CR> the checksum? Or is it the same as the NMEA spec, where the checksum is the XOR (and not the sum) of all the preceding characters?

Thanks
Etienne

 

[dynonsupport]

Your first guess is correct: the checksum is the lower byte of an integer add.

 

[Etienne]

Great, thanks