Connect to the serial device.

def serial_connect(self):
		"""
		Connect to the serial device.
		"""
		self.serial_get()
		try:
			self.serial_connection.start()
		except c1218.errors.C1218IOError as error:
			self.logger.error('serial connection has been opened but the meter is unresponsive')
			raise error
		self._serial_connected = True
		return True