[GTALUG] Problem with /dev/ttyUSB* serial port

[Alvin Starr]

On 10/31/19 2:25 AM, Jim Ruxton via talk wrote:
> I have a device plugged into an active USB extender that usually shows 
> up as /dev/ttyUSB0 when I first plug it in (occasionally it will show 
> up as /dev/ttyUSB1 when first plugging it in) . If it is /dev/ttyUSB0 
> when I unplug it and plug it back in it occasionally changes to 
> /dev/ttyUSB1 . Is there a way that I can always have it show up as 
> /dev/ttyUSB0 . I'm not sure why /dev/ttyUSB0 isn't being released and 
> restarted after unplugging and replugging it. If I look in /dev it 
> does disappear as /dev/ttyUSB0 from there when I unplug it but like I 
> said it reappears as /dev/ttyUSB1? I am on Ubuntu 18.04.3 LTS .
>
> Thanks for any pointers.
My guess would be that if the USB is unplugged or otherwise disrupted 
the kernel will start taking down the interface but this will take some 
time.
If in that intervening time the device is plugged back in then there 
will be some remnants of ttyUSB0 left so the kernel will pick the next 
device ttyUSB1.

You could test this by quickly plugging/unplugging your usb device and 
compare the results to plugging and unplugging with a few second delay 
between the events.

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Alvin Starr                   ||   land:  (647)478-6285
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