/dev/ttyUSB0 spontaneously changes to /dev/ttyUSB1

[Alan Cox]

> as /dev/ttyUSB0.  A wview server attaches to /dev/ttyUSB0 and runs fine
> till suddenly the device disappears from /dev/ttyUSB0 and appears
> as /dev/ttyUSB1, at which time the server fails.  

You need to fix the server.

> I suspect (though without much evidence) that the reason for the device 
> moving around is that there is a brief interruption of service from the
> device, so that it appears to the computer that a *new* device has 
> appeared, which it has to find a device name for before it had deleted
> the old name of the device.

That sounds likely - dmesg will probably tell you.

> Does anyone know of a way to keep the USB device open at a known
> location, maybe by creating a permanent entry in /dev, and bypassing
> udev?  Any more theories about what, in general, is happening?

Even if you overwrote the old device node the server needs to re-open the
file handle. Given the server will get notification that the port has
failed (eg a SIGHUP or going ready for read and getting an error on the
read) it shouldn't be too hard to fix it.

Alan