I have searched across the web and cannot find any 8 Bit CRC code, I can = find 16 Bit but I don't think this will work! I am afraid that working polynomial out, is way above my head! The code I require is X^8 + x^2 + X^1 +1, this does not seem to be the = standard but I assume I would just change a number in the routine?=20 If anyone can help I would be very grateful Thanks Gary -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.