OpenPlotter managed USB device not showing up as serial port in SignalK

[ThorHei]

I was running the Waveshare MAX-M8Q GNSS hat via an UART serial connection to a Raspberry Pi 5 and this worked without problems until it did not anymore. For some reason I cannot get it running anymore via UART but it is still running via a USB connection.

So I installed this now USB connected device again with the "Serial" app in OpenPlotter and can see this connection in the SignalK connections list. In the settings under "Serial port" the alias (/dev/ttyOP_gnss) can be seen in the right box but not in the list of serial ports in the left box where it says "Enter manually" (but I see other OpenPlotter managed (UART) aliases). I can only choose the physical USB connection (e.g., /dev/ttyUSB0) and when doing this the alias disappears in the right box and this box goes grey. Now I get the GNSS data, everything is working fine.

The problem is: When restarting the Raspberry Pi the device may get registered at another USB port (e.g., /dev/ttyUSB1) and therefore the SignalK connection is pointing to the wrong USB port resulting in a missing connection to the GNSS device. When I manually choose the new USB port everything is fine again but as I understand the use of alias device addresses is exactly to prevent the problem with changing physical port addresses.

Could anyone point me to how to solve this issue? Thank you.

(RPi5 with Debian 12/Bookworm, Serial 4.1.0, SignalK Server 2.13.2)

[tkurki]

There should be serialports named with prefix /dev/serial/by-id. These are persistent, unique and stable aliases to serial devices.

[tkurki]

@sailoog any ideas why usb aliases do not show but UART ones do? SK server uses serialport library to list available serial ports but has explicit support for OpenPlotter managed aliases https://github.com/SignalK/signalk-server/blob/master/src/serialports.ts#L70