Checksum CRC-15 for velbus (domotics)

English
1

I am currently using the velbus output relay module (4 outputs). I managed to get the protocol for the commands (in hex) but the second last byte seems random to me. I tried checksum CRC-15 (for CAN BUS) but i still cannot get it. I downloaded the velbus protocol summary (.pdf) and there is a code for language C. I tried to compile it and it doesnt work. Please someone help me.

Thanks

2

Velbus is using two’s complement checksum

Take the sum of all bytes (unsigned) up to the checksum, discarding any overflow bits. Then invert all bits and add 1.

CHECKSUM = (~SUM)+1

3

thanks!!!