Catching ttyUSB changes after modem reboot

[nordeep]

Thank you for your work! Set up gpoint on Kroks KNdRt31R19 with Quectel EP06-E.
Stuck in the next issue: Modem unexpectedly reboots and side effect is remapping ttyUSB ports to new values. As a result gpoint lost connection with GPS receiver. For now trying to stabilize the modem. But maybe any ideas how to catch changes of ttyUSB for gpoint?

[Kodo-kakaku]

Hi @nordeep !
I have not encountered this behavior of Quectel. I can assume that this problem lies in the vendor applications of Kroks itself. The logic of Gpoint working with a modem is to contact the modem on the AT port in order to send a command to start GNSS, then this data is read from the GNSS port...
I wanted to clarify a couple of questions for myself:

• Which version of the Kroks router firmware do you use?
• What is the firmware version of the Quectel modem?
• At what point does an emergency reboot of the modem manifest itself? At the same time, your Internet connection disappears?
• Have you noticed such problems before installing Gpoint?

Thank you for your feedback and interest in the project!

[nordeep]

1. Kroks KNdRt31R19 + sim injector Rt-Cse SIM Injector DS(Kroks KNdRt31R16)
2. Quectel EP06-E firmware - EP06ELAR04A03M4G
3. Modem behavior is disconnect from USB and connect again. Internet connection also reconnect after modem restarts.
4. I think yes. For now we are testing modem without GNSS data. Gpoint is disabled for now.
   We have a discussion with Kroks here - https://4pda.to/forum/index.php?showtopic=994528&st=4320#entry122418164 One of the guess is the unstable PSU.

It has been suggested to use hotplug.d for remap ttyUSB to symlink to let Gpoint/gpsd not to block mapping ttyUSB*

[Kodo-kakaku]

I've been testing Gpoint with the Quectel EP06 modem all day, while overloading it, disconnecting it in an emergency - the ports remained the same. But I remembered that I had encountered similar behavior on another modem and it was caused, in my opinion, by the lack of a sim card. Try to exclude the sim injector, and test the operation without it.

[koshev-msk]

Hi @nordeep!
Probably u question does not directly concern the application.
I propose to use the script in /etc/hotplug.d/usb/ location to create links of modem ports.
See example.
Best regards.