[sane-devel] Sane and microtek2 hangs on large scans

[Edenyard]

   Please could someone help me solve this problem. I have a Microtek
Scanmaker 336 or V310 (badged Philips) connected via the parallel port
to my P166 (64Mb RAM) running Slackware 8.1. I have kernel 2.4.18 patched
with the ppscsi and onscsi patches. I'm running scanimage V1.0.8 and
microtek2 backend V0.95.

   The system recognises the scanner as /dev/sg1 and I can make scans
after a fashion. If I select color at 72 DPI, I can scan a whole sheet
of A4. If I select LineArt at 150 DPI, it works too. However, in color
mode, I cannot scan more than about half an A4 sheet at 150 DPI; at
300DPI, it's down to just a few square inches. If I exceed these
limits, the scanner's head seems to oscillate back and forth over about
a quarter-inch for about 40 seconds. Then the scanner stops, its green
LED goes out; after a few more seconds the prompt returns and I find
that I get a scan file of exactly 37 bytes. The scanner has to be
powered down and up again to reset it. When I succeed with the smaller
areas, the picture quality appears to be fine with no visible errors.

   Originally, I used this scanner with windows 3.1 at 300 DPI to scan a
whole A4 sheet in colour, so I know that the hardware is capable of
doing this. It seems as though something runs out of space under Linux,
though. I'm sure it isn't disk space - there's over 1Gb of spare space
on the partition. Could it be memory?

   I read somewhere that I should add to /etc/profile the line
"export SANE_SG_BUFFERSIZE=1048576". I tried that and rebooted but it
made no real difference. I tried varying the number in powers of 2
downwards once or twice but that didn't cure the problem either.

   I'm at the limit of my technical knowhow with this, so I'd be very
grateful if anyone could suggest what to try next. Thanks in advance!

   Regards,

      Gerald Pye
      mail at edenyard.co.uk