Ok everyone....I have spent many hours trying to figure this out. I am trying to talk to an Entertron PLC through a 18F4550 PIC. I have the serial routine working through a terminal emulator with no problems @ all. But when I connect it to the PLC its not working right. The PLC is receiving commands (the PLC goes into stop mode) but when it sends the "K" back as an acknowledge...the 18F4550 does not receive it (although monitoring the comm between the PLC and PIC.....the PLC is sending back the "K") So the term emulator works throught the routine with out a problem but the PLC will not. Has me stumped........David


Code:
	Define	OSC	20	' 20 MHz oscillator
	
	RCSTA = %00000000
	BAUDCON = %01000000
	ADCON1 = 15		' All I/O pins digital
	   Pause 100
	   
	   
	   
 pause 3000
    :STPCMD
    HIGH PORTD.0
        PAUSE   10
    LOW PORTD.0
    
    Serout2 PORTC.6, 84, [$1B,"S",$d]  'SEND STOP COMMAND S
    SERIN2  PORTC.7, 84, 1000, STPCMD,[WAIT ("K")]
     HIGH   PORTD.1
     
    :DWNLDCMD 
    HIGH PORTD.0
        PAUSE   10
    LOW PORTD.0
    Serout2 PORTC.6, 84, [$1B,"D",$d]  'SEND STOP COMMAND S
    SERIN2  PORTC.7, 84, 1000, DWNLDCMD,[WAIT ("K")]
     HIGH   PORTD.2


'SEND OUT CONFIG REGISTERS FOR TROUBLESHOOTING 
    Serout2 PORTC.6, 84, [$d]  
    Serout2 PORTC.6, 84, [".......BIT7^..BIT0^",$d]  
    Serout2 PORTC.6, 84, ["TXSTA......",BIN TXSTA,$d]  
    Serout2 PORTC.6, 84, ["RXSTA......",BIN RCSTA,$d]  
    Serout2 PORTC.6, 84, ["BAUDCON....",BIN BAUDCON,$d]  
    Serout2 PORTC.6, 84, ["OSCTUNE....",BIN OSCTUNE,$d]  
    Serout2 PORTC.6, 84, ["OSCCON.....",BIN OSCCON,$d]  
    Serout2 PORTC.6, 84, ["PORTC......",BIN PORTC,$d]  
    Serout2 PORTC.6, 84, ["LATC.......",BIN LATC,$d]  
    Serout2 PORTC.6, 84, ["TRISC......",BIN TRISC,$d]  
    Serout2 PORTC.6, 84, ["UCON.......",BIN UCON,$d]
   
    
    
    
    Serout2 PORTC.6, 84, ["HAVE A NICE DAY !",$d]  
    
    STOP