serial port communication

Discussion in 'MFC' started by answerme, Oct 16, 2008.

  1. answerme

    answerme New Member

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    Hye all
    Below I have pasted my C serial port code .
    Iam getting error
    Code:
    Cannot open Communication Port. error no.2 
    .
    error no.2 specifies that system cannot find the file specified.
    Does anyone have suggestion


    Code:
    #include "stdafx.h"
    #include<windows.h>
    #include<winbase.h>
    #include <conio.h>
    
    HANDLE hComm;
    BOOL m_bPortReady;
    DCB  m_dcb;
    COMMTIMEOUTS m_CommTimeouts;
    DWORD iBytesWritten;
    int gle;
    
    BOOL ConfigurePort(DWORD BaudRate, BYTE ByteSize, DWORD fParity, BYTE Parity, BYTE StopBits)
    {
    	if((m_bPortReady = GetCommState(hComm, &m_dcb))==0)
    		{
    			printf("GetCommState Error");getch();
    			CloseHandle(hComm);
    			return false;
    		}
    	m_dcb.BaudRate =BaudRate;
    	m_dcb.ByteSize = ByteSize;
    	m_dcb.Parity =Parity ;
    	m_dcb.StopBits =StopBits;
    	m_dcb.fBinary=TRUE;
    	//m_dcb.fDsrSensitivity=false;
    	m_dcb.fParity=fParity;
    //	m_dcb.fOutX=false;
    //	m_dcb.fInX=false;
    //	m_dcb.fNull=false;
    //	m_dcb.fAbortOnError=FALSE;
    //	m_dcb.fOutxCtsFlow=FALSE;
    //	m_dcb.fOutxDsrFlow=false;
    	//m_dcb.fDtrControl=DTR_CONTROL_DISABLE;
    	//m_dcb.fDsrSensitivity=false;
    	//m_dcb.fRtsControl=RTS_CONTROL_DISABLE;
    	//m_dcb.fOutxCtsFlow=false;
    	//m_dcb.fOutxCtsFlow=false;
    
    	m_bPortReady = SetCommState(hComm, &m_dcb);
    	if(m_bPortReady ==0)
    	{
    		printf("SetCommState Error");getch();
    		CloseHandle(hComm);
    		return false;
    	}
    		return true;
    }
    BOOL SetCommunicationTimeouts(DWORD ReadIntervalTimeout, DWORD ReadTotalTimeoutMultiplier, DWORD ReadTotalTimeoutConstant, DWORD WriteTotalTimeoutMultiplier, DWORD WriteTotalTimeoutConstant)
    {
    if((m_bPortReady = GetCommTimeouts (hComm, &m_CommTimeouts))==0)
       return false;
    m_CommTimeouts.ReadIntervalTimeout =ReadIntervalTimeout;
    m_CommTimeouts.ReadTotalTimeoutConstant =ReadTotalTimeoutConstant;
    m_CommTimeouts.ReadTotalTimeoutMultiplier =ReadTotalTimeoutMultiplier;
    m_CommTimeouts.WriteTotalTimeoutConstant = WriteTotalTimeoutConstant;
    m_CommTimeouts.WriteTotalTimeoutMultiplier =WriteTotalTimeoutMultiplier;
    		m_bPortReady = SetCommTimeouts (hComm, &m_CommTimeouts);
    		if(m_bPortReady ==0){
    printf("StCommTimeouts function failed");getch();
    		CloseHandle(hComm);
    		return false;}
    		return true;
    }	
    
    BOOL WriteByte(char* bybyte)
    {
    	iBytesWritten=0;
    	if(WriteFile(hComm,bybyte,1,&iBytesWritten,NULL)==0)
    		return false;
    	else 
    		return true;
    }
    BOOL ReadByte(char *resp)
    {
    
    	char rx;
    	resp = 0;
    	DWORD dwBytesTransferred=0;
    	if(ReadFile (hComm, &rx, 1, &dwBytesTransferred, 0))
    	{
    		if (dwBytesTransferred == 1)
    		{
    			resp=&rx;
    			return true;
    		}
    	return false;
    	}
    }
    int _tmain(int argc, _TCHAR* argv[])
    {
    	
    	hComm = CreateFile((LPCWSTR)"COM1",
                          GENERIC_READ | GENERIC_WRITE,
                          0,
                          0,
                          OPEN_EXISTING,
                          FILE_FLAG_OVERLAPPED,
    					  0);
    
    	if(hComm==INVALID_HANDLE_VALUE)
    		{
    			printf("Cannot open Communication Port..");
    			gle = GetLastError();
    			printf("error no.%d\n", gle);
    			getch();
    			return false;
    		}
    
    	DWORD data=0; 
    	unsigned char a[2], b[1],buffer[10],sendb[14], *vptr;
    	char *ptr; 
    	char err[4];
    	int slen;
    	char rx = 0;
    	char x[1];
    	char bw;
    	/*short int crcv;//unsigned char* ptr;
    	unsigned char buff[10] = {0x1b,0x81,0x00,0x80,0x00,0x80,0x40,0x00,0x00,0x1};
    	unsigned char buff[10] = {0x30,0x30,0x30,0x30,0x30,0x30,0x30,0x30,0x30,0x30};
    	crcv = Calc_CCITT_CRC(buff, 10);
    
    	ptr = (char*)&crcv;
    	sprintf(a, "%c%c", *ptr, *(ptr+1));
    	sprintf(b, "%c", 0x7e);
    	memcpy(buffer, buff, 10);
    	sendb[0] = (char)0x7e;
    	for(int j = 1; j < 11; j++)
    		sendb[j] = buff[j-1];
    	//free(buff);
    	sendb[11] = (char)*ptr;
    	sendb[12] = (char)*(ptr+1);	
    	sendb[13] = (char) 0x7e;int gle;
    	*a = (unsigned char)0x30; //*(a+1) = (unsigned char)0x32;
    	sprintf(sendb, "%s%s%s%s", b, buff, a, b);
    	CString dsend = CString(b)+ CString(buff) + CString(a) + CString(b);*/
    	char dsend = char(a);//sendb);
    	b[0] = 0x31;
    	vptr = (unsigned char*)&b;
    
    	
    	if(!ConfigurePort(9600, 8, 0, NOPARITY, ONESTOPBIT))
    	{
    		printf("Cannot Configure Communication Port");
    		getch();
    		CloseHandle(hComm);
    	}
    	else
    	{
    	if(!SetCommunicationTimeouts(1000,1000,1000,1000,1000))
    	{
    		printf("Cannot Configure Communication Timeouts");
    		getch();
    		CloseHandle(hComm);
    	}
    	else
    	{
    	if(!WriteByte(&dsend))
    	{
    		printf("Cannot Write to Port");
    		int gle = GetLastError();
    		sprintf(err, "%x", gle);
    		getch();
    		CloseHandle(hComm);
    	}
    	else
    	{
    		sprintf(x, "%x",dsend);
    		printf("Success%c",x);
    		if(!ReadByte(&bw))
    		printf("Timeout on getting Response.Please ensure that\nyou have connected the loop back plug to com1.");
    	else 
    	{
    		memset(x, 0, 1);
    		printf("Successfully Read from Com1");
    		sprintf(x,"%x", bw);
    		printf("Read Byte %c",x);
    		getch();
    		CloseHandle(hComm);
    	}
    	}
    	}
    	}
    	}
    
     
  2. oogabooga

    oogabooga New Member

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    It would be useful if you tell us where you got the bulk of the code from so we could see the original (which presumably works).

    This looks wrong:
    (LPCWSTR)"COM1"
    Try this:
    TEXT("COM1")

    Also, your if/else if structure has more braces than necessary. This:
    Code:
    if()
    {
    }
    else
    {
      if()
      {
      }
      else
      {
        if()
        {
        }
        else
        {
          if()
          {
          }
          else 
          {
          }
        }
      }
    }
    Is usually written like this:
    Code:
    if()
    {
    }
    else if()
    {
    }
    else if()
    {
    }
    else if()
    {
    }
    else 
    {
    }
    Or, since each if is testing for failure, it is even cleaner like this:
    Code:
    if (!FirstThing())
    {
        ...
        exit (1);
    }
    
    if (!SecondThing())
    {
        ...
        exit (2);
    }
    
    if (!ThirdThing())
    {
        ...
        exit (3);
    }
    
    if (!FourthThing())
    {
        ...
        exit (4);
    }
    
    // Success
    ...
    return 0;
     
  3. Cosmic_egg

    Cosmic_egg New Member

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  4. Cosmic_egg

    Cosmic_egg New Member

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