COM port strange behavior

[Corsair63]

W11 ARM64 O 5.9.0,

FTB I have two connections to autopilot just for testing autorouting:
1 - direct to multiplexer (Miniplex 3E N2K) via SeaTalk
2 - direct via COM port to PC (COM7 4800,n,1,p), USB adaptor.
set-up priority as preferred multiplexer and spare COM port.

sometimes happens very strange thing:
started computer and everything fine, no USB problem, etc.
started O, and displayed O.S. message that USB device not recognised (the one for COM7)
checked in settings - connections - NMEA debug window and receiving the proper data from COM7 (is that sorcery?)
if I close O I could not access to COM7 (using Termite or another software using that COM port, of course not simultaneously) until I restart computer.
of course, done unplug & plug the USB connection and same message of not recognised USB device.

also noticed when this happens, I have watchdog running with two wind alarm as apparent and T-R, in normal session both then work but when this happens the wind alarm T-R shows N/A.

for now, it has happened not more than four times in one month time.

[wholybee]

5.9.0 is not released yet. It is possible it is related to you not using a stable release. (devs would probably still be interested in your experience, though) Does this problem occur on 5.8.4?

Odd behavior similar to that is why I always try to use USB Com port devices that the the FTDI chipset. There seem to be bugs in other chipsets that create odd intermittent behavior, COM ports disappearing, or numbering changing.

Unfortunately the chipset used isn't always apparent. But try to dig into what the Com7 USB adapter is using and if not FTDI, try a different one that is.

[Corsair63]

I'm not at the boat now, but as far as I remember all USB/Com ports are using FTDI driver for ARM64.

as you should be aware windows ARM64 is complicated about drivers and even more with COM port ones, because all of them must be compiled for ARM64 and digitally signed, otherwise not accepted by the system itself.

I cannot tell if that happens in 5.8.4 because I have no computer using that version all them using 5.9.0 and also not tested in W11 x64, because those computers are not connected on board.