[sane-devel] [PARTIALLY SOLVED] I/O error using saned over net

[widman]

True, but the same kds driver works correctly when invoked directly.
I was hoping that greater minds than mine could suggest a way to
proceed. For example, perhaps there is a timing issue when kds is
invoked by saned that is not present when it is invoked by scanimage.
If, for example, the read process is initiated too soon after scanner
initialization, the first page may not be read correctly. Even without
access to the kds source, someone familiar with scanners may suggest
a way to ferret out the problem so that saned can be modified to overcome
the problem.

A secondary purpose of posting the patch was to provide a way for others
to work around the problem now if it happens to help them. Being able to
scan N-1 pages over the net is far better than 0 pages!

Thanks for your quick reply and for your support of this project.  I
will be happy to try things that readers may suggest.

On Wed, Nov 02, 2011 at 08:29:28AM -0400, m. allan noah wrote:
> The bigger question is why does the kds driver return
> SANE_STATUS_JAMMED when the scanner is not jammed. Since it is closed
> source, we cannot know.
> 
> On Tue, Nov 1, 2011 at 11:42 PM, widman <widman at cecst.com> wrote:
> >  ....
> >  1. Locally, scanimage -L
> >     detected the scanner correctly.
> >  2. Locally, scanimage --device-name kds:i1210/i1220 --batch=foo%d.pnm
> >     scanned every page correctly into local files.
> >  3. Locally, scanimage --device-name net:localhost:kds:i1210/i1220 --batch=foo%d.pnm
> >     failed with "scanimage: sane_read: Error during device I/O."
> >  4. Over the net, scanimage --device-name net:<ip of server>:kds:i1210/i1220 --batch=foo%d.pnm
> >     failed with "scanimage: sane_read: Error during device I/O."
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