No activity on IO Debug port for Pixhawk 4 fmu-v5

I am looking to read PX4_ERR messages and assume I would read them over the IO Debug port on the side of my Pixhawk 4. I hooked pin 4 (pixhawk tx) and pin 5 (pixhawk rx) to an oscilloscope and saw no activity with tx reading high and rx reading low. When I connected it to the computer with an ftdi adapter and putty I could see keyboard strikes on rx but still no activity on tx. Is there something I need to do to activate debugging?

I assume you want to debug PX4_ERR “printfs” of the FMU side (not IO side)? In that case you need to connect the FTDI adapter (or Dronecode Debug probe) to the “FMU Debug” port.

Thanks I am getting some messages now.

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Dear Julian

Coud you help me please.
After an unsuccessful firmware flashing using QGC. Through the IO Debuging port (after usb pluging) I see the following messeges:


through the port FMU debufer

Leds of PX following (only blue led is flickers, the rest are solid).

When I firmware setup throug QGC everything looks good


But in fact, the device does not flash anymore after the last unsuccessful firmware 08/21/19

On the device panel, the PX4 vice is recognized as MindPX.

Could you please tell what happened with Pixhawk4. It is necessary to burned the bootloader through the programmer and how can this be done?

Best regards,
Muzalevskiy Konstatnin

Follow up in Pixhawk 4 board seems bricked