.tlog file not playable with MissionPlanner (APMPlanner2 can play it)

From time to time, I get telemetry logs that are not playable with MissionPlanner. I think, it might have to do something with data corruption during the connection process (UDP), because it only happens when I connect the aircraft using my long range system (DragonLink). Nevertheless, while flying, the ground station displays the data as expected and I have good signal strength.

After the flight, I can open the .tlog file (which has a normal file size) and hit the play/pause button or push the slider around, but there is no data displayed. There is no aircraft symbol on the map, the HUD is not moving and so on. Although some things are okay, e.g. the “reached command number …” voice messages.

I am sure, that all information are contained in the file, because it is playable with APMPlanner2. So why can’t MissionPlanner play the file?

Here is a telemetry log with the described problem:

Hi Felix
I played the .tlog file with my MissionPlanner. You are right it is not good. For me it looks that something with your PreArm check is not compatible with MP. Do you have a hardware safety switch?
The voice is telling you to press the hardware safety switch for a long time. ( about 3 minutes) There are EKF, Mission command numbers, Waypoint messages, low Battery and finally a Battery failsafe info.
During all those voice messages as you have discovered yourself the HUB shows only the timer and signal strengths moving.
But I read from start to finish DISARMED and NO GPS. The file is definitely corrupted by the Telemetry radio or MissionPlanner is halted by failded preArmcheck!?
But I am guessing here strongly, I have no experience with your kind of Telemetry radio.

Hi Fred!

Thanks a lot for taking the time to analyze my telemetry log. Yes, I do have a hardware safety switch. It just took so long to start up and check all my systems. I’m using the preflight checklist feature in MP and needed to work through the list.

It seems, that the problem occurred before the prearm checks. After connecting to MissionPlanner all the numbers (e.g. in the “quick” or “status” tab) should update. When I replay the log it always says “0.00”.

I did a second flight right after the flight with the corrupted log and everything is fine there. I didn’t change anything, so I don’t really know, what went wrong.

But as I said, APMPlanner2 can replay the log without problems. So all information are contained. It’s just a minor corruption that holds MP back of reading it in the correct way. The other question is: Why did MP write a corrupted log although the flight displays looked good while flying?

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Hi Felix,

did you come up with a reason for the strange behaviour of mission planner with playing telemetry logs?
I currently experience similar issues with my Orange Cube, as no particular information is being displayed on the HUD of mission planner when playing telemetry logs.
Interestingly, when I run the FC directly via USB on the GCS, telemetry logs seem to be recorded correctly and playback is possible - this behavior obviously does not help for logs of flights…

I further realized that while loading the current telemetry logs, it says “INFO MissionPlanner.MAVLinkInterface - ID sys 1 comp 0 ver3 type ADSB name INVALID”, instead of logs the can be backplayed that state “INFO MissionPlanner.MAVLinkInterface - ID sys 1 comp 1 ver3 type FIXED_WING name ARDUPILOTMEGA”.

Any clue on the problem and a solution?

Hi Pascal,

no, unfortunately I couldn’t find a solution for the problem. But I concluded, that it is caused by a bad telemetry connection, maybe dropped packets or something like that. I am using the DragonLink v3 for both RC signals and telemetry connection. The connection between transmitter and helicopter is really stable and reliable, but the WiFi connection between the WiFi module of the DragonLink and my notebook always seems to be a little problematic. On some days it’s fine, but sometimes I have to try multiple times, until I get a connection and can download the parameters. Unfortunately, I could never figure out, what the problem is. I even updated the firmware of the wifi module, of the DragonLink, changed the streamrates, disabled and enabled flow control, checked the correct pinout for a working flow control… without success. Maybe I could try an external WiFi module or use Bluetooth instead.

In your case, I would suggest, to check your telemetry connection at first. What system are you using? Are there other transmitters near your telemetry antenna?

The second question is: Why can’t MP play the logs, although they definitely contain all information? As I already wrote, APMPlanner2 can play them without problems. So if you only need the contained information, you could get them with APMPlanner2. But that’s only a workaround of course.


open MP
start playback
in the top right, select helicopter.

and it will work as you expect.

it apears to be selecting whatever other mavlink enabled device you have connected by default

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Oh, thank you so much, Michael! That really is working! I would never have believed, that it is so easy, but that definitely is the solution! Thank you!!

Thanks Michael,
I only saw your answer today, but it really solves my struggle, I had the last months.