Posted on 1998-08-21
Last Modified: 2010-04-10
I am trying to write a RS232 interface in c++.  Is there any source code for this already on the web?
Question by:SJW082198
LVL 22

Expert Comment

ID: 1170887
For what platform?

Expert Comment

ID: 1170888
What platform?

Author Comment

ID: 1170889
Windows 95

Expert Comment

ID: 1170890
I'm not sure if there are any source on the web, but I can tell you a short list of functions which might help you :
CreateFile, CloseHandle,
GetCommState, SetCommState,
GetCommTimeouts , SetCommTimeouts
WriteFile, ReadFile ... etc.
Or you can read the following chapter in Platform SDK :
Windows Base Services\Hardware\Communications or
Windows Base Services\Files and I/O\Communications
LVL 14

Accepted Solution

AlexVirochovsky earned 50 total points
ID: 1170891
Hi, here is 3 simple programmes for Read/Write to RS232

static int idComDev = -1;
static DCB  dcb;

#define MAX_LEN_INPUT   1200
#define MAX_LEN_OUTPUT  1200
void DefineRS232(void)
  int err,;
    *szInit = "COM1:9600, N, 8, 1",
    buff[20];                  //Com Command

  wsprintf(buff, "COM%d", i+1);
  idComDev = OpenComm(buff,MAX_LEN_INPUT , MAX_LEN_OUTPUT);
  if (idComDev >= 0)  //open?
      err = BuildCommDCB(szInit, &dcb);
      if (err >= 0)
      err = SetCommState(&dcb);
      if (err < 0)                        //Error?
        idComDev  = -1;
void WriteRS232(char *s)
  if (idComDev >= 0)                  //OK?
    {                                    //send acknoledge
      err = WriteComm(idComDev,(LPCSTR)s,strlen(s));
      if (err < 0)             //error: close
        idComDev = -1;      //no!
void ReadRS232(char *buff)
  int err = ReadComm (idComDev,buff,MAX_LEN_OUTPUT);
  if (err < 0)             //error: close
      idComDev = -1;      //no!

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