# how to user SER\_F

**URL:** <https://forums.digi.com/t/how-to-user-ser-f/9603>\
**Category:** Rabbit\
**Created:** [March 28, 2011, 10:39am UTC](https://forums.digi.com/t/how-to-user-ser-f/9603 "2011-03-28T10:39:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ignazioc](https://avatars.discourse-cdn.com/v4/letter/i/45deac/32.png) [@ignazioc](https://forums.digi.com/u/ignazioc)\
**Post date:** [March 28, 2011, 10:39am UTC](https://forums.digi.com/t/how-to-user-ser-f/9603/1 "2011-03-28T10:39:00Z")

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hi, i have 5600 demo board and usa this program to write on serial ports

```auto

#class auto

/ *****************************************************
     The input and output buffers sizes are defined here. If these
     are not defined to be (2^n)-1, where n = 1...15, or they are
     not defined at all, they will default to 31 and a compiler
     warning will be displayed.
****************************************************** /
#define CINBUFSIZE 15
#define COUTBUFSIZE 15
#use "rcm56xxw.lib"

#define LEDON 0
#define LEDOFF 1
#define DS1 0

void main()
{
   char h,l;
   h = 'U';
    serFopen(9600);
   brdInit();

   while (1) {
      serXwrite(SER_PORT_F, &amp;h, 1);
     costate
		{

                //blink led	     
              BitWrPortI(PDDR, &amp;PDDRShadow, LEDON, DS1);
			waitfor(DelayMs(100)); // On for 50 ms.
	      BitWrPortI(PDDR, &amp;PDDRShadow, LEDOFF, DS1);
			waitfor(DelayMs(100)); // Off for 100 ms.
		}

   }
}

```

why my signal exit on ser\_c port ???

---

<div class="post-metadata">

**Author:** ![petermcs](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@petermcs](https://forums.digi.com/u/petermcs)\
**Post date:** [March 28, 2011, 12:52pm UTC](https://forums.digi.com/t/how-to-user-ser-f/9603/2 "2011-03-28T12:52:18Z")

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By default serial port F will use the port C pins for RX/TX if you want to use another port you must define the SERF\_TXPORT and SERF\_RXPORT macros.

For example, in the RCM5700 port of the BACnet stack I use the following to select serial port F as the port to use instead of port D and have it use the PORT E pins (the same would apply to the RCM5600W).

#define ALT\_RCM5700\_SER 1

#if ALT\_RCM5700\_SER  
#define SERF\_TXPORT PEDR  
#define SERF\_RXPORT PEDR  
#define FINBUFSIZE 1023 // start out with big buffers and serial port F  
#define FOUTBUFSIZE 1023  
#endif

Regards,  
Peter