"m. allan noah" <[email protected]> wrote: >> In this case, the product ID will differ between the 2 hardwares (if >> they're totally different, at least), or we can hope so. (talking of >> USB here, as for everything else there's really no means to guess) > > no, you hope for too much. there are cases where manuf. makes changes
I hope that, in this case, the changes aren't too significant, that's all. I learned the hard way that there's nothing you can hope from hardware vendors (although some obviously behave better than others). > to equipment capabilities (running changes) but does not update the Hmm. There's a revision information along with the VID/PID which basically covers this need. Is that usable in this situation ? (ie do vendors care to update this one ?) > PID. perhaps this case cannot be helped, and perhaps Oliver is right, > that the backend will have to make options to disable these features. Yep. > then the serial number is useless to the discussion. the only reason > to get it, is situations where there are multiple of the same scanner > being used on a machine, and each needs a slightly different > calibration. if per-scanner configs (gamma tables, etc) were stored by > serial number this would work, even when the scanner switches ports or > from scsi to usb. > > in order for this to work, the backend needs to be able to uniquely ID > the unit. This is needed too in cases where several identical scanners are connected to the same host. If only the USB spec made it mandatory to have a unique device identifier :( [haven't read the spec for a long time now, but I don't think something alike exists in the spec] JB. -- Julien BLACHE <http://www.jblache.org> <[email protected]> GPG KeyID 0xF5D65169
