NMEA Checksum Calculator
This function node expects a string in msg.payload sentence without "$" and "*".
For example: msg.payload = GPGLL,3751.65,S,14507.36,E
It will then calculate the checksum, convert the checksum from Decimal to HEX and add this together with the "$" and "*" to msg.payload.
var checksum = 0; for(var i = 0; i < msg.payload.length; i++) { checksum = checksum ^ msg.payload.charCodeAt(i); } msg.payload = "$" + msg.payload + "*" + checksum.toString(16); return msg;
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