Hi @florian.pix, I am also unable to start the micrortps_client per my previous post.
After accessing the pixhawk’s nsh> through mavlink_shell.py from my companion computer, I get the following error when trying to start the micrortps_client:
nsh> micrortps_client status
INFO [micrortps_client] Not running
nsh> micrortps_client start -t UART
INFO [micrortps_client] UART transport: device: /dev/ttyACM0; baudradevice reports readiness to read but returned no data (device disconnected or multiple access on port?)
This error is originating from .local/lib/python3.8/site-packages/serial/serialposix.py
This error occurs every time I try to start the micrortps_client - whether through the mavlink shell or QGC console. The Pixhawk disconnects from QGC and plays the error tune. The connection between the Pixhawk 4 and the companion computer (a Raspberry Pi running Ubuntu 20.04) is a usb cable into the side port.
I just saw your posted solution; not sure if it applies here but I will try that and report back.