void getDatastream(MAVLink.MAV_DATA_STREAM id, byte hzrate)
        {
            mavlink_request_data_stream_t req = new mavlink_request_data_stream_t();
            req.target_system = MAV.sysid;
            req.target_component = MAV.compid;

            req.req_message_rate = hzrate;
            req.start_stop = 1; // start
            req.req_stream_id = (byte) id; // id

            // send each one twice.
            generatePacket((byte) MAVLINK_MSG_ID.REQUEST_DATA_STREAM, req);
            generatePacket((byte) MAVLINK_MSG_ID.REQUEST_DATA_STREAM, req);
        }

        /// <summary>
        /// Stops all requested data packets.
        /// </summary>
        public void stopall(bool forget)
        {
            mavlink_request_data_stream_t req = new mavlink_request_data_stream_t();
            req.target_system = MAV.sysid;
            req.target_component = MAV.compid;

            req.req_message_rate = 10;
            req.start_stop = 0; // stop
            req.req_stream_id = 0; // all

            // no error on bad
            try
            {
                generatePacket((byte) MAVLINK_MSG_ID.REQUEST_DATA_STREAM, req);
                System.Threading.Thread.Sleep(20);
                generatePacket((byte) MAVLINK_MSG_ID.REQUEST_DATA_STREAM, req);
                System.Threading.Thread.Sleep(20);
                generatePacket((byte) MAVLINK_MSG_ID.REQUEST_DATA_STREAM, req);
                log.Info("Stopall Done");
            }
            catch
            {
            }
        }