Hi Darrel,
Its 2mS for the whole CRC routine. I simply toggle a pin at the start of the subroutine and again at the exit. It is working through 8 or so bytes to calculate the CRC value.

Out of interest, could you expand upon the line :-
IF CRC.0(CRC_Len-1) THEN
I don't understand the purpose or method of the code in parenthesis.

Thanks,
Tim.