1. I have a HoverGames drone running PX4 v1.13.2 and
2. An offboard developer system (NavQ Plus) sustained by Ubuntu 22.04 and running ROS2 Humble
3. The micrortps_client (on PX4) and micrortps_agent (on offboard computer) are installed and are able to communicate through serial interface.

3A. When I run micrortps_client status in PX4 shell I can see rx: 0.460 Kb/s and tx: 11.709 Kb/s. If micrortps_agents is not executed I have rx: 0.0 Kb/s 3B. Or in the final when I close, trhough Ctrl + C, micrortps_agent I get:

[ micrortps_agent ] Interrupt signal (2) received.

[ micrortps_transport ] Closed UART.

[ micrortps_agent ] RECEIVED: 2570 messages - 3770846 bytes; 322869 LOOPS - 326.422 seconds - 11.55KB/s

[ micrortps_agent ] SENT: 3261 messages - 169572 bytes

My personal conclusion, from 3A and 3B, is that micrortps_client and micrortps_agent are able to communicate and exchange data without any problems.

I do not know if it helps, but when micrortps_agent runs, I get continuously:

[ micrortps_agent ] Unexpected topic ID ‘27’ to publish. Please make sure the agent is capable of parsing the message associated to the topic ID ‘27’

Now, the problem:

1. By running: ros2 topic list (I'm in ~/ros2_ws and . install/setup.sh was previously executed), and
2. If export RMW_IMPLEMENTATION=rmw_fastrtps_cpp is presented in .bashrc I get only:

/parameter_events

/rosout

1. If instead I export:

   export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

   export CYCLONEDDS_URI=/home/$USER/CycloneDDSConfig.xml

I get also only:

/parameter_events

/rosout

So, the problem is that I'm unable to get any topics even if micrortpsis apparently working. I would appreciate any solution or insight on this problem.