Hello All, I’m working with a Pixhawk cube connected to a dragon link (the newest 1W receiver) coupled to a slim v3 dragon link transmitter, connected to QGroundcontrol (attempted this on a PC and android tablet, both USB and bluetooth, various settings including starting with the recommended ones). I am not able to reliably get the full initial parameter load, and often during the initial connection get communication lost messages. Once connected it gives telemetry and doesn’t seem to lose it, but with QGroundcontrol obviously limited. If I’m in the right area to post I can add more information, but I’m wondering has anyone used dragon link for bidirectional telemetry reliably? If so, what settings have you used please?
Alex,
I have used DragonLink fairly successfully w/ Pixhawk 2.1, DragonLink micro receiver, and Mission Planner, though not w/out frustrations. I can’t get detailed settings at the moment, but I believe I’ve generally follow the recommendations; could you post your settings? Also, have you tried it w/ Mission Planner or are you on Linux? I pretty much exclusively use it in USB mode rather than Bluetooth because we had issues w/ that.
Hello Scott,
Thank you for your reply and the information. I think we in the past used the micro receiver successfully, and had similar issues with Bluetooth. It seems when we upgraded to the new large 1.5W receiver and the v3 slim transmitter we lost good telemetry. OK let me correct - we can ‘get’ telemetry in terms of the HUD and such, but parameter loading almost never succeeds. It fails to get about 10 random parameters during initial load. I started with the recommended settings from the dragon link page and diy drones. I can post those in a bit but perhaps the link is best -
http://www.dragonlinkrc.com/instructions/v3equipment/pixhawktelemetry/
http://www.dragonlinkrc.com/instructions/v3equipment/telemetryoptions/
We wish we could use the USB mode but the android doesn’t seem to recognize the dragon link transmitter. I think an FT232 is supported in android on QGC by default so that should work but I haven’t had success getting a connection yet.
I have used both android and win/mac systems with the issue being equivalent across computer systems. One of my friends just informed me he increased the serial baud rate over the recommended 19.2kbps and that helped. I’ve tried going slower but not increasing actually.
Mission planner doesn’t give this error but doesn’t run on android, which is our deployment target as part of the system. However a developer of QGC seems to think that mission planner might just not be reporting the lost variables. That is not confirmed yet via experiments. Thanks for any input.
Best,
Alex
Alex,
I have a 1.5W receiver for a future vehicle and will try to play around w/ it tomorrow. I’ll only be able to test on QGroundControl on PC though.
Also, what do you mean by QGroundControl being limited? Does it look like it not getting all those parameters is indicative of other problems or does not having them affect performance somehow? I’m just curious because I know we’ve had times where MP was able to “connect” and data showed up on the HUD, but there was quite a bit missing from the “Status” section.
Regards,
Scott
Hello Scott,
I got it working. The baud rates must be 57.6k on all settings. Dragon link’s setup page doesn’t appear to work well in this case. I’ll post details tomorrow. Have to finish things for a demo tomorrow so I’ll get back to you on your questions. QGC presents a limited interface if it can’t get all parameters, similarly with MP. I had the same type of issue in the past - HUD but parameter problem.
Best,
Alex
PS - there were also some issues on dragon link external connection setup. I had to connect directly FT232 to pixhawk and then back out correct settings a stage at a time.
Hi Alex, I appreciate this discussion was awhile ago but I’ve an issue connecting DL V3 slim transmitter ( non bluetooth) to mission planner via usb as I don’t have Bluetooth version. No matter what I change in dragon link GUI (external connection settings) it won’t connect. It keeps going into that 28 second count down trying to connect. And I know the micro receiver is connected properly to pixhawk flight controller because I’m getting reading from it. Could you please help, giving some info about the steps with ftdi might help. dragonlink hasn’t bothered replying for the last 2 weeks!
Many thanks in advance
Hello Andre,
I understand your frustration. We similarly had some trouble getting timely replies from DL. Ultimately I did succeed in getting the most robust connection possible but had some problems with losing telemetry packets that seemed like it was coming from the DL, so we have moved to a different radio, and haven’t had issues since. We were also using a second data link for video and experienced some definite interference, though in theory they should have worked together ok according to all the documentation (and theory). I’ll look back on my settings. It was a few issues in the long run keeping it from connecting. I’ll be happy to let you know, though please be patient as my time is limited these days - I have a little startup and a new baby keeping me busy:) I’ve been thinking of writing a little tutorial up since we had such issues, it might save people some time (at least, one that addresses the issues I had - there are a few tutorials out there but somehow they ignore these problems), it has just been a time issue.
A few important points to consider before I go look up all the details are
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Be sure that you have set the telemetry to be the radio option not mavlink.
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To output on USB you have to set telemetry to be sent through that port
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If you are using an android device, you may need to use an FTDI usb to serial adapter connected to the external serial port (I think it was the UEXP port), as our tablet didn’t have the driver for their USB device, but supported FTDI without any effort
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If you use the FTDI adapter, use the port settings you’d use for the 3dr telemetry radio. There are many tutorials out there on that so no need to repeat here I think. The key takeaway is that the telemetry radio connection settings are typically built into most major drone programs since it’s so common
Well hopefully this gets you started. Also double check that the serial lines are connected correctly and check the grounding. I’ll check on the settings when I have a moment and please let me know if you get it going in the meantime.
Best,
Alex