Maybe you could use 0 like an escape character or backslash, so that 0,0 is interpreted as the RGB value of 0 and 0,255 (say) is interpreted as end of packet. Then you could send your example string as 234,0,0,100,45,21,94,0,255 which would mean 234, 0, 100, 45, 21, 94, END.