[sane-devel] genesys:libusb:.... changes while scanning (sane)

[n d]

Hi,
So I created simple udev rules:
ATTR{product}=="CanoScan", KERNEL=="2-5.1", SYMLINK+="bus/usb/002/SCANNER1"
ATTR{product}=="CanoScan", KERNEL=="2-5.2", SYMLINK+="bus/usb/002/SCANNER2"
ATTR{product}=="CanoScan", KERNEL=="2-5.3", SYMLINK+="bus/usb/002/SCANNER3"
ATTR{product}=="CanoScan", KERNEL=="2-5.4", SYMLINK+="bus/usb/002/SCANNER4"

now scanimage -L give the next result:
device `genesys:libusb:002:013' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:014' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:015' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:016' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:SCANNER1' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:SCANNER4' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:SCANNER2' is a Canon LiDE 700F flatbed scanner
device `genesys:libusb:002:SCANNER3' is a Canon LiDE 700F flatbed scanner

when scanning for the first time (lets say calling to
 `genesys:libusb:002:SCANNER1' it works)
but when trying to call to the rest of the scanners i get error messages
like

scanimage: open of device genesys:libusb:002:SCANNER2 failed: Invalid
argument
or
scanimage: sane_start: Invalid argument

that happens *manually* too.

any idea?

tnx alot.



On Mon, Jan 27, 2014 at 3:07 PM, Richard Ryniker <ryniker at alum.mit.edu>wrote:

> >Is there any way to give each scanners a persistent (and informative)
> >name?
>
> Udev is the general mechanism for this.
> https://en.wikipedia.org/wiki/Udev gives an overview.
>
> >does anyone have some idea why the usb numbering changes while running
> >the script? (tried to run the commands manually one by one, no change in
> >scanners name for this case)
>
> Probably a timing issue.  Your script performs some USB activity, then
> again before the device has completely finished.  The second operation
> (busy device) confuses the software, which resets to put the device into
> a known state (this causes the new device number).  When you execute
> commands from your script manually, the extra time allows completion of
> device activity and no reset occurs.
>
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