USB Port Wierdness

[phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org]

We have our oscilloscope project working nicely over a USB line, using an
FTDI usb-serial adaptor chip in the scope hardware. From our tcl program,
we simply open /dev/ttyUSB0 and treat it as a serial port.

However, this only works reliably when operating as root.

When operating as a normal user, ever time we plug and unplug the the USB
cable, the permissions on /dev/ttyUSB0 revert back to root-only use.
Furthermore, whether /dev/ttyUSB0 is even present varies: sometimes other
ports are present, but not that one.

We tried 'mknod /dev/ttyUSB0 c 188 o' but this wierd behaviour doesn't
change.

It looks as if the files in /etc/udev might have something to do with how
dynamic ports get assigned, but I'm not enough of an expert to tell.

Has anyone else dealt with this? It would probably be a problem with any
serial to usb converter cable.. BTW, all this is taking place using Suse
9.1 on an IBM laptop.

Thanks -
Peter

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