Rover: Sonar data not present in telemetry data (always zero)

I have a Pixhawk 2.1, ECT400, Mission Planner 1.3.72, ArduRover V3.4.2,
Windows 10. I did all the setup according to the documentation. When I
connect the ECT400 to my PC, it works. However, when I connect it to Pixhawk,
Mission Planner shows sonar range = 0 and sonar voltage = 0. I have a
Sparkfun rs232 to serial converter, it looks OK. I tried to examine it with
an oscilloscope, ECT400 definitely sending some messages. What could be the
Thank you and best regards,

Hi, Have you set all the parameters on the Pixhawk which are mentioned here.

Hello, yes, I did. At the moment, I can decode all the messages with an Arduino Mega (converter and echo are okay), but not with Pixhawk. I even tried different versions of ArduRover and Mission Planner with no results…

Make sure:

  • You have not accidentally reverse the RX and TX lines to the pixhawk
  • You’ve correctly set which port it’s connected to in Mission Planner (SERIAL2,3,4 etc)