Dual telemetry, unable to write to both at the same time

I have a need for 2 independent telemetry links connected to Navio, but when the 1st link is established the next link to establish on another telemetry “port”, cannot write(in the Mavlink transaction sense) any data back to Navio, only receive telemetry.

Is this expected behavior?

Best regards
Paulo Neves@airborneprojects.com

Could you give us a little more insight into your setup? Is telemetry transmitted via radio, 4G, Wi-Fi or Ethernet? The way you launch APM might also be relevant. You might want to look at this thread about problems with radio connection.

The link seems irrelevant but they are both through UDP connections. One is an UDP connection to loopback and the other, an UDP connection through wireless. The behavior surfaces depending on which one connects last.


The underlying APM driver is a little bit off at the moment. I’m in progress of a major refactoring effort in order to solve some issues regarding UDP-connection.
At the moment the behavior you’re witnessing is expected. One of the links is a supplementary. What’s your eventual desire? If I understand correctly, both channels do work but you’re able to communicate with a vehicle from GCS only with one of them?

Your understanding is correct, both channels work but only one is able to start MAVlink transactions.
What we want is to be able to have to GCSs connected through independent UDP connections.
If you point me to the github files in ArduCopter what needs to be done, I may have it done and send a pull request for you to verify.

Just a tip. Have you tried to disable / uninstall the ifplugd?
To be able to communicate with two interfaces simuntanusly e.g eth0 and wifi, ifplugd has to be disabled. I dont know if this applies for loopback though.

I doubt it is such a problem because the network is reachable and the second GCS can receive the datastream, so the network is well configured. ifplugd would be a network level problem that would make the Raspberry PI unreachable to the GCS.

Thanks anyway :slight_smile: