Debugging

This page describes how to debug an issue with your MOD unit. Contents apply to both MOD Duo X and MOD Dwarf units.

Logs

Assuming the unit is able to boot and you have SSH access, the following can be used for dumping information about the unit.

sshpass -p mod ssh -o StrictHostKeyChecking=no root@192.168.51.1 "journalctl -m" > syslogs.txt

UART debug

By opening the unit it is possible the locate RX/TX/GND pins on the bottom-board of the unit.
You can solder pins to these holes in order to read and write to the UART console.

Note that the HMI (device controller) makes uses of this UART interface for a few of its operations, so it will misbehave if you connect something to the TX pin (as this blocks the HMI side from sending data).
Connecting to TX and GND is safe, which allows the HMI to keep working and for us to still listen/read the UART debug logging.

For enabling early kernel boot logs, ssh into the unit and run the following:

# mount RW
mount / -o remount,rw

# enable verbose kernel logs
sed -i -e 's/quiet //g' -e 's/loglevel=0/loglevel=9/g' /boot/uEnv-*.txt

# sync and reboot unit
sync; hmi-reset; reboot

The kernel logs will now be sent to the console, allowing to monitor any kernel/boot issues via UART.