[PLUG] Scanner dependent on USB port

Alan alan at clueserver.org
Sun Feb 2 19:47:30 UTC 2020


On Sun, 2020-02-02 at 06:18 -0800, Rich Shepard wrote:
> My desktop host has an Asus Prime X470-Pro motherboard and USB3.x
> ports on
> the rear panel plus two on the front panel.
> 
> I have a 7-port USB3.x hub connected to one of the rear ports. The
> external
> backup drive, Palm TX sync/charger, and the Nokia phone charger are
> connected to that hub. But, when I connect the Canon Canoscan LiDE
> 400 to
> the hub neither 'scanimage -L' nor 'sane-find-scanner' sees it.
> 
> Connecting the scanner to a front port results is different:
> 
> $ scanimage -L
> device `pixma:04A91912_4301BD' is a CANON CanoScan LiDE 400 multi-
> function peripheral
> 
> $ sane-find-scanner
> ...
> found USB scanner (vendor=0x04a9 [Canon], product=0x1912 [LiDE 400])
> at libusb:001:098
> 
> This series of Canon scanners is now supported by sane-1.0.28 which I
> built
> from the source code in a clone of sane's github repo.
> 
> I don't now know which flavor of USB3.x powers the hub and front port
> and
> wonder why this would make a difference in sane (and I presume xsane)
> finding the scanner.

Scanners are weird. Most/all drivers cannot be seen if they are on a
USB hub. This includes Windows. I am not certain why. It wants the
shortest path to the device for some reason. 




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