Trying to use tlog writer for my own transmissions

[neilyoung]

My tlogWriter setup (snip off):

	dialectRW := &dialect.ReadWriter{Dialect: ardupilotmega.Dialect}
	err := dialectRW.Initialize()

	if err != nil {
		log.Errorf("Failed to initialize dialect: %v", err)
		return err
	}
	mc.dialectRW = dialectRW

	file, err := os.Create("output.tlog")
	if err != nil {
		return err
	}

	writer := &tlog.Writer{
		ByteWriter: file,
		DialectRW:  mc.dialectRW,
	}
	err = writer.Initialize()
	if err != nil {
		return err
	}
	mc.tlogWriter = writer

	return nil

With that output.tlog is created and I'm able to log each incoming message like so (snip off):

				if frm, ok := evt.(*gomavlib.EventFrame); ok {

					mc.logIncomingFrame(frm.Frame)

whereas

func (mc *MavlinkClient) logIncomingFrame(f frame.Frame) {
 
	if mc.tlogWriter == nil {
		return
	}

	var copy frame.Frame

	switch v := f.(type) {
	case *frame.V2Frame:
		var sig *frame.V2Signature
		if v.Signature != nil {
			s := *v.Signature
			sig = &s
		}
		copy = &frame.V2Frame{
			IncompatibilityFlag: v.IncompatibilityFlag,
			CompatibilityFlag:   v.CompatibilityFlag,
			SequenceNumber:      v.SequenceNumber,
			SystemID:            v.SystemID,
			ComponentID:         v.ComponentID,
			Message:             v.Message,
			Checksum:            v.Checksum,
			SignatureLinkID:     v.SignatureLinkID,
			SignatureTimestamp:  v.SignatureTimestamp,
			Signature:           sig,
		}
	case *frame.V1Frame:
		copy = &frame.V1Frame{
			SequenceNumber: v.SequenceNumber,
			SystemID:       v.SystemID,
			ComponentID:    v.ComponentID,
			Message:        v.Message,
			Checksum:       v.Checksum,
		}
	default:
		return
	}

	err := mc.tlogWriter.Write(&tlog.Entry{
		Time:  time.Now(),
		Frame: copy,
	})
	if err != nil {
		log.Warnf("tlog write (incoming) failed: %v", err)
	}
}

That works fine!

Now I'm trying to also log my outgoing message, so messages like this one (snip off):

	// Prepare the command message
	msg := &ardupilotmega.MessageCommandLong{
		TargetSystem:    sysID,
		TargetComponent: compID,
		Command:         cmd,
		Confirmation:    0,
	}

	log.Infof("Sending COMMAND_LONG msgID=%d type=%T", msg.GetID(), msg)

	if p.Params.Param1 != nil {
		msg.Param1 = float32(*p.Params.Param1)
	}
	if p.Params.Param2 != nil {
		msg.Param2 = float32(*p.Params.Param2)
	}
	if p.Params.Param3 != nil {
		msg.Param3 = float32(*p.Params.Param3)
	}
	if p.Params.Param4 != nil {
		msg.Param4 = float32(*p.Params.Param4)
	}
	if p.Params.Param5 != nil {
		msg.Param5 = float32(*p.Params.Param5)
	}
	if p.Params.Param6 != nil {
		msg.Param6 = float32(*p.Params.Param6)
	}
	if p.Params.Param7 != nil {
		msg.Param7 = float32(*p.Params.Param7)
	}

	mc.logOutgoingMessage(msg)

whereas

func (mc *MavlinkClient) logOutgoingMessage(msg message.Message) {
	if mc.tlogWriter == nil {
		return
	}

	fr := &frame.V2Frame{
		SystemID:    mc.sysID,    
		ComponentID: mc.compID,    
		Message:     msg,          
	}

	
	err := mc.tlogWriter.Write(&tlog.Entry{
		Time:  time.Now(),
		Frame: fr, 
	})
	if err != nil {
		log.Warnf("tlog write failed: %v", err)
	}
}

I'm getting a log entry, for instance when sending the ARM command, but mavlogdump.py complains about missing/wrong CRC:

2025-05-22 22:03:58.83: BAD_DATA {invalid MAVLink CRC in msgID 76 0x0000 should be 0xf33b, data:['fd', '20', '0', '0', '0', '1', '1', '4c', '0', '0', '0', '0', '80', '3f', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '90', '1', '1', '1', '0', '0']}

Can somebody give me a pointer, how to create an entry with a valid CRC?

[neilyoung]

One step more: Could make it run, but it is insane: I first need to derive the crcExtra() from the message, which isn't too complicated. Then I need to convert my msg of type frame.Message to RawMessage in order to be able to call fr.GenerateCRC().

But finally it works, I'm just mad with the Message->RawMessage transition step

Working agains ArduPilotSimulator (Set Mode Guided, ARM, Mission Clear All, Mission Upload, Mission Start here):

$ mavlogdump.py output.tlog
2025-05-22 23:34:27.16: COMMAND_LONG {target_system : 1, target_component : 1, command : 176, confirmation : 0, param1 : 1.0, param2 : 4.0, param3 : 0.0, param4 : 0.0, param5 : 0.0, param6 : 0.0, param7 : 0.0}
2025-05-22 23:34:28.32: COMMAND_LONG {target_system : 1, target_component : 1, command : 400, confirmation : 0, param1 : 1.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, param5 : 0.0, param6 : 0.0, param7 : 0.0}
2025-05-22 23:34:31.33: MISSION_CLEAR_ALL {target_system : 1, target_component : 1, mission_type : 0}
2025-05-22 23:34:32.08: MISSION_CLEAR_ALL {target_system : 1, target_component : 1, mission_type : 0}
2025-05-22 23:34:32.09: MISSION_COUNT {target_system : 6, target_component : 0, count : 257, mission_type : 0}
2025-05-22 23:34:32.11: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 0, frame : 0, command : 16, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : -353632608, y : 1491652352, z : 50.0, mission_type : 0}
2025-05-22 23:34:32.12: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 1, frame : 3, command : 22, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : -353632608, y : 1491652352, z : 50.0, mission_type : 0}
2025-05-22 23:34:32.13: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 2, frame : 3, command : 16, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : -353623584, y : 1491627904, z : 50.0, mission_type : 0}
2025-05-22 23:34:32.14: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 3, frame : 3, command : 16, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : -353617024, y : 1491643520, z : 50.0, mission_type : 0}
2025-05-22 23:34:32.15: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 4, frame : 3, command : 16, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : -353619552, y : 1491655680, z : 50.0, mission_type : 0}
2025-05-22 23:34:32.17: MISSION_ITEM_INT {target_system : 1, target_component : 1, seq : 5, frame : 3, command : 20, current : 0, autocontinue : 1, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, x : 0, y : 0, z : 0.0, mission_type : 0}
2025-05-22 23:34:39.20: COMMAND_LONG {target_system : 1, target_component : 1, command : 300, confirmation : 0, param1 : 0.0, param2 : 0.0, param3 : 0.0, param4 : 0.0, param5 : 0.0, param6 : 0.0, param7 : 0.0}

I hope somebody will say: Idiot, it is that easy, look here...:)

[aler9]

Hello, if you want to log a frame, the frame must be valid. If you build frames in this way:

	fr := &frame.V2Frame{
		SystemID:    mc.sysID,    
		ComponentID: mc.compID,    
		Message:     msg,          
	}

They are missing the checksum. There's an utility to recompute the checksum, that is Node.FixFrame(), that requires a Node instance, therefore:

func (mc *MavlinkClient) logOutgoingMessage(msg message.Message, node *gomavlib.Node) {
	fr := &frame.V2Frame{
		SystemID:    mc.sysID,    
		ComponentID: mc.compID,    
		Message:     msg,          
	}
	node.FixFrame(fr)
}

[neilyoung]

I think I solved that mesnwhile. Thanks