Hi..
thank u alot I lik [Always wear safety glasses while programming]

I forget to tell u I am new in PICBASIC PRO now only 2 weeks. I think the code will be like this:
define osc 4
include "bs2defs.bas"

wait:
SERIN PORTa.1,N9600,["K3"],myVar
IF myVar = 3 THEN out

out:
HIGH PORTb.7
PAUSE 300
LOW PORTb.7
goto wait

but I cant understand [myvar]. How I can decide it???
Thank u in advance.