Not sure what you mean by datapin...
But..
On the receive side you are only checking the serial port once,
Code:
SERIN2 PORTA.5\PORTA.1, 3313, [DEC X]
LOOP1:     
   HIGH PORTD.2
   PAUSE X
   LOW PORTD.2
   PAUSE X
GOTO LOOP1
Put the SERIN2 line inside of LOOP1.