`mavsdk_server` does not connect over serial until QGC is started

[xindax2000]

I want to join the Pixhawk with MAVsdk. I use the following command: ./mavsdk_server -p 50051 serial:///dev/ttyACM1:57600 => does NOT start... just waiting If I open and close QGroundControl, than It works!!! If I don't open QGroundControl, then it won't start.

What schould I do? How do I start it?

[dayjaby]

You have to disable any kind of autoconnect on the serial ports in QGroundControl first.

The best method to find the culprit in cases like this is to use lsof:

sudo apt install lsof
sudo lsof /dev/ttyACM0

[JonasVautherin]

I want to join the Pixhawk with MAVsdk.

PX4 or Ardupilot? I'm assuming PX4.

If I open and close QGroundControl, than It works!!!

I do believe that over serial, PX4 needs to receive MAVLink messages before it starts sending them. I think this is fairly new, though. I guess mavsdk_server should automatically send heartbeats when connecting over serial. Not sure... @julianoes do you have an opinion here?

[xindax2000]

Yes, PX4 how can i cause heartbeat?

[JonasVautherin]

I think you would want to set always_send_heartbeats, using set_configuration maybe somewhere around here?

[xindax2000]

I don't fully understand this

[julianoes]

@JonasVautherin should we make a bugfix release for this?

[JonasVautherin]

I guess it would be nice to test it first. Also we should do it only for serial://, shouldn't we?

[xindax2000]

Yes, PLS!

[julianoes]

@JonasVautherin, yes but it's not straightforward I'm afraid.

[xindax2000]

Did you manage to solve it?

[julianoes]

This should be fixed in https://github.com/mavlink/MAVSDK-Python/releases/tag/1.4.4.