Connect to the serial port.

def _connect(self):
        """Connect to the serial port."""
        try:
            while True:
                _LOGGER.info('Trying to connect to %s', self.port)
                try:
                    yield from serial_asyncio.create_serial_connection(
                        self.loop, lambda: self.protocol, self.port, self.baud)
                    return
                except serial.SerialException:
                    _LOGGER.error('Unable to connect to %s', self.port)
                    _LOGGER.info(
                        'Waiting %s secs before trying to connect again',
                        self.reconnect_timeout)
                    yield from asyncio.sleep(
                        self.reconnect_timeout, loop=self.loop)
        except asyncio.CancelledError:
            _LOGGER.debug('Connect attempt to %s cancelled', self.port)