[sane-devel] multiple scanners

[Sergey Vlasov]

(Sorry, I'm always forgetting to use "Reply to list" :-( )

On Fri, 17 Jan 2003 16:07:28 +0100
Henning Meier-Geinitz <henning@meier-geinitz.de> wrote:

> Hi,
> 
> On Fri, Jan 17, 2003 at 05:35:22PM +0300, Sergey Vlasov wrote:
> > On Fri, 17 Jan 2003 11:27:12 +0100
> > Henning Meier-Geinitz <henning@meier-geinitz.de> wrote:
> > 
> > > > Does SANE support multiple scanner types at the same time?
> > > 
> > > Yes. Basically, the number of scanners is unlimited. I've succeeded in
> > > scanning from 3 USB and 3 SCSI scanners at the same time :-)
> > 
> > Hmm. Looking at the Linux USB scanner kernel driver, I suspect that
> > the device scan would be blocked in open() when it hits an used
> > device.
> 
> I dond't think so. The locks are only active during the call to
> open_scanner(), not while the device is open. Scanning an already
> opened device will run into the  "if (scn->isopen)" test and exit.
> At least that's the case in recent kernels.
> 
> The following example with three scanners works here:
> 
> $ scanimage -L
> device gt68xx:/dev/usb/scanner2' is a Plustek OpticPro 1248U flatbed  scanner
> device gt68xx:/dev/usb/scanner1' is a Mustek BearPaw 2400 CU Plus flatbed scanner
> device gt68xx:/dev/usb/scanner0' is a Mustek ScanExpress 1200 UB Plus flatbed scanner
> 
> $ scanimage -d gt68xx:/dev/usb/scanner0 >/tmp/image0.pnm & \
>   scanimage -d gt68xx:/dev/usb/scanner1 >/tmp/image1.pnm & \ 
>   scanimage -d gt68xx:/dev/usb/scanner2 >/tmp/image2.pnm

But what if you do 'scanimage -L' while some scanning is in progress?