def setBufferSize(self, rx_size=4096, tx_size=None):
"""\
Recommend a buffer size to the driver (device driver can ignore this
vlaue). Must be called before the port is opended.
"""
if tx_size is None: tx_size = rx_size
win32.SetupComm(self.hComPort, rx_size, tx_size)
def open(self):
"""Open port with current settings. This may throw a SerialException
if the port cannot be opened."""
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 %r: %r" % (self.portstr, ctypes.WinError()))
try:
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)
# 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._reconfigurePort()
# Clear buffers:
# Remove anything that was there
win32.PurgeComm(self.hComPort,
win32.PURGE_TXCLEAR | win32.PURGE_TXABORT |
win32.PURGE_RXCLEAR | win32.PURGE_RXABORT)
except:
try:
self._close()
except:
# ignore any exception when closing the port
# also to keep original exception that happened when setting up
pass
self.hComPort = None
raise
else:
self._isOpen = True
def set_buffer_size(self, rx_size=4096, tx_size=None):
"""\
Recommend a buffer size to the driver (device driver can ignore this
value). Must be called before the port is opened.
"""
if tx_size is None:
tx_size = rx_size
win32.SetupComm(self._port_handle, rx_size, tx_size)
