Read raw data from the serial connection. This function is not
		meant to be called directly.

		:param int size: The number of bytes to read from the serial connection.

def read(self, size):
		"""
		Read raw data from the serial connection. This function is not
		meant to be called directly.

		:param int size: The number of bytes to read from the serial connection.
		"""
		data = self.serial_h.read(size)
		self.logger.debug('read data, length: ' + str(len(data)) + ' data: ' + binascii.b2a_hex(data).decode('utf-8'))
		self.serial_h.write(ACK)
		if sys.version_info[0] == 2:
			data = bytearray(data)
		return data