code: def on(self):
          
          on_command = ExtendedSend(self._address,
                                    COMMAND_LIGHT_ON_0X11_NONE,
                                    self._udata,
                                    cmd2=0xff)
          on_command.set_checksum()
          self._send_method(on_command, self._on_message_received)
docs: Send an ON message to device group.