ECT400 setup on serial port 4/5

Hi, I follow this instructions:
in order to get ecosounder to work on pixhawk. I’m using telem 1 and 2 for raspi and telemetry, so I have to connect it to serial port 4.
But, I don’t get any reading. I’m using qground control (I’m on linux) and showing “distance” using Widget->analyze tool.
I’ve checked that aerial pulses are coming from ECT to pixhawk with my oscilloscope. I test the setup with usb-uart converter and CuteCom.