Serial port

[JimmyK]

Hi all,
I want to set baud rate of COM1 port, write something to COM1, and "listen" reply from devices connected to COM1.

How can i so that? please give a simple example

Jimmy

Thank you in advance

 

[foxjoker]

Hi Jimmy !

You can use the function CreateFile to open the port :

hComm=CreateFile(ComName,dwDesiredAccess,0,NULL,OPEN_EXISTING,FILE_FLAG_OVERLAPPED,NULL);
[\code]
This is an example to set up the port, but you should see the functions definitions :
[code]
	cc.dcb.BaudRate=CBR_115200;
	cc.dcb.ByteSize=8;
	cc.dcb.Parity=NOPARITY;
	cc.dcb.StopBits=ONESTOPBIT;

	if(!VerifySetup())
		return false;

	if(!SetDefaultCommConfig(nameport,&cc,sizeof(COMMCONFIG)))
		return false;
	SetCommState(hComm,&cc.dcb);
	return true;
[\code]

To listen to devices connected to the port, you should create a thread that reads character from the port.

This function reads one character from the port :
[code]
	DWORD NbBytesRead;
	COMSTAT comstat;
	DWORD errors;

	ClearCommError(hComm,&errors,&comstat);

	if (!comstat.cbInQue)
		return false;
	
	while (true)
	{
		if (!(ReadFile(hComm,buffer,1,&NbBytesRead,&o_read)))
		{
		//if the io operation is not terminated, it waits until it is

			NbBytesRead=0;
			if(GetLastError()==ERROR_IO_PENDING)
			{
				if(GetOverlappedResult(hComm,&o_read,&NbBytesRead,true))
				{					
					if (NbBytesRead)
						return true;
				}
			}
		
			else
			{
				MessageError(GetLastError());
				return false;
			}
		}
		else
			if (NbBytesRead)
				return true;
		ResetEvent(o_read.hEvent);
	}
	PurgeComm(hComm, PURGE_RXCLEAR);
	return false;
[\code]

I hope this can help you.

 

[JimmyK]

Thanks FoxJoker,
It really helps.

Jimmy