Serielle Datenausgabe mit C

Hallo!

Ich suche seit einiger Zeit verzweifelt ein Codebeispiel oder eine Erklärung wie man mit C Zeichenketten über die Serielle Schnittstelle des PCs an die Außenwelt schicken kann.
Ich muss dazu Einstellungen wie Baudrate, Anzahl der Daten- & Stopbits sowie die Parität vornehmen können.
Aus einigem herumsuchen bin ich auf die WinAPI gestoßen, aber ich hab leider keine Tutorien zur Datenausgabe für C gefunden
Eventuell hat jemand von euch Ahnung bzw. Erfahrung mit diesem Thema uns kann mir helfen?

danke auf alle Fälle schon mal im Voraus!

Wutz

ANSI C kennt keinen seriellen Port und demzufolge auch keine Kommunikation damit.
Wenn du schon WINAPI Funktionen gefunden hast, warum nimmst du diese nicht? Das sind üblicherweise C Funktionen, wenn auch überwiegend nicht striktes ANSI C.

pointercrash**

Da bist Du hier falsch.
Guckst Du Bei anderer Ecke RS232 Basics.
Da sind auch weiterführende Links zu finden. Und wenn's für Win sein soll, im MSDN ist auch ein lesenswerter Abschnitt.

Hier ein CPP-Code für Win

/*
 * Version 1.0
 * <hdieterm yahoo de>
 */

/*
 * list of return codes:
 * 00 Success
 * 01 User Interrupt (Esc-Key)
 * 02 Timeout
 * 03 COM not open
 * 04 COM is allready open
 * 05 COM wrong interrupt
 * 06 COM wrong baud rate
 * 07 COM no char received
 * 08 COM WriteFile error
 * 09 COM ReadFile error
 * 10 COM CreateFileA error
 * 11 COM GetCommState error
 * 12 COM SetCommState error
 * 13 COM GetCommTimeouts error
 * 14 COM SetCommTimeouts error
 * 15 COM PurgeComm error
 * 16 COM PeekNamedPipe error
 * 20 COM unknown error message
 */

#include "stdafx.h"
#include "rs232win.h"
#include "time.h"

static HANDLE hCom = INVALID_HANDLE_VALUE;
static int port_open = 0;  /* 0 = closed  1 = open */
static int comerror = 0;
static double timeout_default;

const char *comerror_description(int ret)
{
	static char tmp[64];

	switch (ret) {
		case 0:  sprintf(tmp,"00 Success"); break;
		case 1:  sprintf(tmp,"01 User Interrupt (Esc-Key)"); break;
		case 2:  sprintf(tmp,"02 Timeout"); break;
		case 3:  sprintf(tmp,"03 COM not open"); break;
		case 4:  sprintf(tmp,"04 COM is allready open"); break;
		case 5:  sprintf(tmp,"05 COM wrong interrupt"); break;
		case 6:  sprintf(tmp,"06 COM wrong baud rate"); break;
		case 7:  sprintf(tmp,"07 COM no char received"); break;
		case 8:  sprintf(tmp,"08 COM WriteFile error"); break;
		case 9:  sprintf(tmp,"09 COM ReadFile error"); break;
		case 10: sprintf(tmp,"10 COM CreateFileA error"); break;
		case 11: sprintf(tmp,"11 COM GetCommState error"); break;
		case 12: sprintf(tmp,"12 COM SetCommState error"); break;
		case 13: sprintf(tmp,"13 COM GetCommTimeouts error"); break;
		case 14: sprintf(tmp,"14 COM SetCommTimeouts error"); break;
    case 15: sprintf(tmp,"15 COM PurgeComm error"); break;
    case 16: sprintf(tmp,"16 COM PeekNamedPipe error"); break;
		default: sprintf(tmp,"20 COM unknown error message"); break;
	}

	return &tmp[0];
}

int comsetreadtimeout(double timeout)
{
  COMMTIMEOUTS cto;
  memset(&cto, 0, sizeof(cto));
  if (!GetCommTimeouts(hCom, &cto)) {
    comerror = 13;
		goto out;
  }

  cto.ReadTotalTimeoutConstant = (unsigned int)(timeout * 1000);
  cto.WriteTotalTimeoutConstant = 0;

  if (!SetCommTimeouts(hCom, &cto)) {
    comerror = 14;
		goto out;
  }

	comerror = 0;

out:
	return comerror;
}

int cominit(char *port, int speed)
{
  DCB dcb;

	if (port_open == 1) {
	  comerror = 4;
		goto out;
	}

  hCom = CreateFileA(port, GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);

  if (hCom == INVALID_HANDLE_VALUE) {
	  comerror = 10;
		goto out;
  }

  if (!GetCommState(hCom, &dcb)) {
	  comerror = 11;
		goto out;
  }

  /* Fill in DCB: (speed) bps, 8 data bits, no parity, and 1 stop bit. */
  dcb.BaudRate = speed;           /* set the baud rate */
  dcb.ByteSize = 8;               /* data size, xmit, and rcv */
  dcb.Parity = NOPARITY;          /* no parity bit */
  dcb.StopBits = ONESTOPBIT;      /* one stop bit */

  if (!SetCommState(hCom, &dcb)) {
    comerror = 12;
		goto out;
  }

	timeout_default = 0.8;  /* 0.8 seconds */
	comerror = comsetreadtimeout(timeout_default);
  if (comerror) goto out;

	port_open = 1;

	comerror = 0;

out:
	return comerror;
}

int comclose(void)
{
	if (port_open == 0) {
    comerror = 3;
		goto out;
	}

  CloseHandle(hCom);
  hCom = INVALID_HANDLE_VALUE;
	port_open = 0;

	comerror = 0;

out:
	return comerror;
}

int comflush()
{
	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

  if (!PurgeComm(hCom,PURGE_TXCLEAR)) {
    comerror = 15;
		goto out;	 	  
	}

  if (!PurgeComm(hCom,PURGE_RXCLEAR)) {
	  comerror = 15;
		goto out;	 
	}

	comerror = 0;

out:
	return comerror;
}

int comreadline(char tmp[], unsigned int maxsize)
{
	unsigned long ret_bytes;
	unsigned int i = 0;
	unsigned char b;
	int c;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	for (;;) {
	  ret_bytes = 0;
		if (!ReadFile(hCom, &b, 1, &ret_bytes, NULL)) {
      comerror = 9;
		  goto out;	
		}

		if (ret_bytes == 1) {
		  if (b == 13) break;
			tmp[i++] = b;

			if (i == maxsize) break;
		}

    if (_kbhit()) {
			c = _getch();
			if (c == 27) { 
				comerror = 1;
				goto out;
			}
		}
	}

	tmp[i] = 0;
	comerror = 0;

	return comerror;

out:
	tmp[0] = 0;
	return comerror;
}

int comwriteline(const char tmp[])
{
	unsigned long ret_bytes = 0;
	unsigned long i = 0;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	comerror = comwritebyte(13);
	if (comerror) goto out;
	comerror = comwritebyte(10);
	if (comerror) goto out;

	while (tmp[i] != 0) {
		i++;
	}

  ret_bytes = 0;
  if (!WriteFile(hCom,tmp,i,&ret_bytes,NULL)) {
    comerror = 8;
		goto out;
	}

	if (ret_bytes != i) {
	  comerror = 8;
		goto out;
	}

	comerror = 0;

out:
	return comerror;
}

int comread(unsigned char tmp[], unsigned int nsize)
{
	unsigned long ret_bytes;
	unsigned int i = 0;
	int c;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	for (;;) {
	  ret_bytes = 0;
		if (!ReadFile(hCom, &tmp[i], nsize - i, &ret_bytes, NULL)) {
			comerror = 9;
			goto out;
		}

		i += ret_bytes;

		if (i == nsize) break;

		if (_kbhit()) {
			c = _getch();
			if (c == 27) { 
				comerror = 1;
				goto out;
			}
		}
	} 

  comerror = 0;

out:
	return comerror;
}

int comread_timeout(unsigned char tmp[], unsigned int nsize, int timeout)
{
	unsigned long ret_bytes;
	unsigned int i = 0;
	int c;

	clock_t timestart, timeend;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	timestart = clock();

	for (;;) {
	  ret_bytes = 0;
		if (!ReadFile(hCom, &tmp[i], nsize - i, &ret_bytes, NULL)) {
      comerror = 9;
		  goto out;
		}

		i += ret_bytes;

		if (i == nsize) break;

		timeend = clock();

		if (((timeend - timestart) / CLK_TCK) > 1) {
			timestart = clock();
			timeout--;
		}

		if (timeout == 0) {
      comerror = 2;
		  goto out;		  
		}

		if (_kbhit()) {
			c = _getch();
			if (c == 27) { 
				comerror = 1;
				goto out;
			}
		}
	}

  comerror = 0;

out:
	return comerror;
}

int comreadbyte(unsigned char *tmp)
{
	unsigned long ret_bytes;
	int c;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	for (;;) {
	  ret_bytes = 0;
	  if (!ReadFile(hCom, tmp, 1, &ret_bytes, NULL)) {
      comerror = 9;
		  goto out;	
		}

		if (ret_bytes == 1) break;

		if (_kbhit()) {
			c = _getch();
			if (c == 27) { 
				comerror = 1;
				goto out;
			}
		}
	}

	comerror = 0;

out:
	return comerror;
}

int comreadbyte_timeout(unsigned char *tmp, int timeout)
{
	unsigned long ret_bytes;
	int c;
	clock_t timestart, timeend;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	timestart = clock();

	for (;;) {
	  ret_bytes = 0;
	  if (!ReadFile(hCom, tmp, 1, &ret_bytes, NULL)) {
      comerror = 9;
		  goto out;
		}

		if (ret_bytes == 1) break;

		timeend = clock();

		if (((timeend - timestart) / CLK_TCK) > 1) {
			timestart = clock();
			timeout--;
		}

		if (timeout == 0) {
      comerror = 2;
		  goto out;		  
		}

		if (_kbhit()) {
			c = _getch();
			if (c == 27) { 
				comerror = 1;
				goto out;
			}
		}
	}

  comerror = 0;

out:
	return comerror;
}

int comreadbyte_nowait(unsigned char *tmp)
{
	unsigned long ret_bytes;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	ret_bytes = 0;
	if (!ReadFile(hCom, tmp, 1, &ret_bytes, NULL)) {
    comerror = 9;
		goto out;	
	}

  if (ret_bytes == 0) {
    comerror = 9;
		goto out;	
	}	

  comerror = 0;

out:
	return comerror;
}

int comwrite(const unsigned char tmp[], unsigned int nsize)
{
	unsigned long ret_bytes;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	ret_bytes = 0;
  if (!WriteFile(hCom,tmp,nsize,&ret_bytes,NULL)) {
    comerror = 8;
		goto out;	 
	}

	if (ret_bytes != nsize) {
    comerror = 8;
		goto out;	 
	}

	comerror = 0;

out:
	return comerror;
}

int comwritebyte(const unsigned char tmp)
{
	unsigned long ret_bytes;

	if (port_open == 0) {
    comerror = 3;
		goto out;	  
	}

	ret_bytes = 0;
  if (!WriteFile(hCom,&tmp,1,&ret_bytes,NULL)) {
    comerror = 8;
		goto out;
	}

	if (ret_bytes != 1) {
    comerror = 8;
		goto out;
	}

	comerror = 0;

out:
	return comerror;
}

und die header datei:

/*
 * Version 1.0
 * <hdieterm yahoo de>
 */

#include "windows.h"
#include "stdio.h"
#include "conio.h"

#ifndef _RS232WIN_H_
#define _RS232WIN_H_ 1

/*
 * list of return codes:
 * 00 Success
 * 01 User Interrupt (Esc-Key)
 * 02 Timeout
 * 03 COM not open
 * 04 COM is allready open
 * 05 COM wrong interrupt
 * 06 COM wrong baud rate
 * 07 COM no char received
 * 08 COM WriteFile error
 * 09 COM ReadFile error
 * 10 COM CreateFileA error
 * 11 COM GetCommState error
 * 12 COM SetCommState error
 * 13 COM GetCommTimeouts error
 * 14 COM SetCommTimeouts error
 * 15 COM PurgeComm error
 * 16 COM PeekNamedPipe error
 * 20 COM unknown error message
 */

const char *comerror_description(int ret);

int cominit(char *port, int speed);
int comclose(void);
int comflush(void);

int comreadline(char tmp[], unsigned int maxsize);
int comwriteline(const char tmp[]);

int comread(unsigned char tmp[], unsigned int nsize);
int comread_timeout(unsigned char tmp[], unsigned int nsize, int timeout);

int comwrite(const unsigned char tmp[], unsigned int nsize);

int comreadbyte(unsigned char *tmp);
int comwritebyte(const unsigned char tmp);

int comreadbyte_nowait(unsigned char *tmp);
int comreadbyte_timeout(unsigned char *tmp, int timeout);

#endif

Ich habe auch eine Version für DOS (C-Code)
Bei Bedarf werde ich diesen veröffentlichen