Another bit of information:The scanner does not have an on/off switch. If I unplug the power and plug it back in, the "hotplug" module changes the permissions to:
-rw------- 1 erwin root 50 Nov 14 21:24 004which means that the scanner works both for the user logged in when the scanner was "power-cycled", and for root.
The question then is how one could trigger this permission change while logging in to the local console.
Erwin