Hello! I have several functions for working with COM-port. Here is a small listing, that I used in C++ Builder:

Qt Code: 
  1. //function for opening COM-port
  2. void COMOpen(portname)
  3. {
  4.    DCB dcb;                
  5.    COMMTIMEOUTS timeouts;  //structure for timeouts
  6.  
  7. //open COM-port!
  8.    COMport = CreateFile(portname.c_str(),GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
  9.  
  10.    if(COMport == INVALID_HANDLE_VALUE) {            //if error
  11.      QMessageBox::warning(this, "Error", "No such COM!"); 
  12.       return;
  13.    }
  14. }
  15.  
  16. //function for closing COM-port
  17. void COMClose()
  18. {
  19.    CloseHandle(COMport);                 
  20.    COMport=0;				
  21.    handle=0;				
  22. }
  23.  
  24.  
  25. on_pushButton_clicked() // function send pulse on button click
  26. {
  27.      COMOpen(portname);  //initialized and open port
  28.  
  29.        int i;
  30.        EscapeCommFunction(COMport, SETDTR); //set hight level DTR
  31.        ui->label->setText("Sending pulse to com-port..."); //sign about sending pulse
  32.        i=0;
  33.        while (i<3000000) { // wait a little, pulse should have a duration
  34.           i++;
  35.           Application->ProcessMessages();
  36.        }
  37.        EscapeCommFunction(COMport, CLRDTR); // free DTR pin
  38.        ui->label->setText(""); //pulse finished, so remove label
  39.       COMClose(portname); //close COM-port 
  40.  
  41. }
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When I include the code to Qt creator I get errors. I'm novice in Qt. Could someone make simple example, which open COM1, for instance, with this code? Thanks a lot!