def open(self):
        if self._port is None:
            raise SerialException("Port must be configured before it can be used.")
        if self._isOpen:
            raise SerialException("Port is already open.")
        # the "\\.\COMx" format is required for devices other than COM1-COM8
        # not all versions of windows seem to support this properly
        # so that the first few ports are used with the DOS device name
        port = self.portstr
        try:
            if port.upper().startswith('COM') and int(port[3:]) > 8:
                port = '\\\\.\\' + port
        except ValueError:
            # for like COMnotanumber
            pass
        self.hComPort = win32.CreateFile(port,
               win32.GENERIC_READ | win32.GENERIC_WRITE,
               0, # exclusive access
               None, # no security
               win32.OPEN_EXISTING,
               win32.FILE_ATTRIBUTE_NORMAL | win32.FILE_FLAG_OVERLAPPED,
               0)
        if self.hComPort == win32.INVALID_HANDLE_VALUE:
            self.hComPort = None    # 'cause __del__ is called anyway
            raise SerialException("could not open port %s: %s" % (self.portstr, ctypes.WinError()))

        # Setup a 4k buffer
        win32.SetupComm(self.hComPort, 4096, 4096)

        # Save original timeout values:
        self._orgTimeouts = win32.COMMTIMEOUTS()
        win32.GetCommTimeouts(self.hComPort, ctypes.byref(self._orgTimeouts))

        self._rtsState = win32.RTS_CONTROL_ENABLE
        self._dtrState = win32.DTR_CONTROL_ENABLE

        self._reconfigurePort()

        # Clear buffers:
        # Remove anything that was there
        win32.PurgeComm(self.hComPort,
                            win32.PURGE_TXCLEAR | win32.PURGE_TXABORT |
                            win32.PURGE_RXCLEAR | win32.PURGE_RXABORT)

        self._overlappedRead = win32.OVERLAPPED()
        self._overlappedRead.hEvent = win32.CreateEvent(None, 1, 0, None)
        self._overlappedWrite = win32.OVERLAPPED()
        #~ self._overlappedWrite.hEvent = win32.CreateEvent(None, 1, 0, None)
        self._overlappedWrite.hEvent = win32.CreateEvent(None, 0, 0, None)
        self._isOpen = True
Open port with current settings. This may throw a SerialException
dataset/ETHPy150Open Robot-Will/Stino/stino/pyarduino/base/pyserial/serialwin32.py/Win32Serial.open