I made the following change in the WHILE loop to allow me to exit. As mentioned, I use the receive register and poll it for the command. Does work, just not as elegant as I would prefer. Addition in red.

Code:
BEGINSCAN:  'START SCANNING PIEZO1
   '
    WHILE SCAN = TRUE
    PAUSE 1
       if RCREG1 = "F" THEN 
         SCAN = FALSE
         RETURN
       ENDIF   
    WEND
RETURN