Thanks skimask, I would have like to add up the keydata but using serial out wouldn't the packets be allowed only 8bits wide or can I send I Word 16bits wide. In that way if all of the keydata bits 0-7 were = to %11111111 then if I added them together the sum would be 10111111010 right? If I made checksum a word and stored it as %0000010111111010,
transmitted it after the last keydata, then on the rx I could :
checksum var word
if ((Keydata1 + keydata2) + (keydata3 + keydata4) + (keydata5 + keydata6)) = checksum then
datagood = 1
else
datagood = 0
endif

would this work? I thought I read somewhere I could only send a byte out not a word, if that is the case couldn't I split the word into two bytes.

Thanks again