Benq Scanner 5000 works from time to time

[Oleg]

Hi all!

I use:
Benq Scanner 5000
sane-backends-1.0.21 
FreeBSD 7.4-STABLE
'firmware /home/user/ftp/20F8V119.bin' in snapscan.conf

The problem is scanner works unstable (from time to time). It takes multiple attepts of 'scanimage > file.ppm' to get the scan. Only 'lsusb' can always see the scanner while 'sane-find-scanner' and 'scanimage -L' can see it from time to time.
I've tried changing firmware to 20F8V116.bin, 20F8V114.bin, 20F8V112.bin - the problem repeats.
The scanner works fine under Windows 7 and Linux (Slax 6.1.2 LiveCD, sane 1.0.20), so the hardware is ok, probably it is OS-related problem. In sane's [sane-devel] mailing list i got recommendation to ask on some freebsd forums.

All my actions have been tested in 2 cases:
1. with libusb (kernel without 'device uscanner') 
2. with uscanner:
(echo 'product ACERP ACERSCAN_5000 0x20f8 Benq 5000' >> /usr/src/sys/dev/usb/usbdevs 
echo '{{ USB_VENDOR_ACERP, USB_PRODUCT_ACERP_ACERSCAN_5000 }, 0 },' >> /usr/src/sys/dev/usb/uscanner.c
recompiled kernel with 'device uscanner')

Case1: 
Benq 5000 powered on first time:

# lsusb
Bus /dev/usb2 Device /dev/ugen0: ID 04a5:20f8 Acer Peripherals Inc. (now BenQ Corp.) Benq 5000

sane-find-scanner found the scanner on the fourth attempt:

# sane-find-scanner -q
# sane-find-scanner -q
# sane-find-scanner -q
# sane-find-scanner -q
found USB scanner (vendor=0x04a5 [Color], product=0x20f8 [ FlatbedScanner 22]) at libusb:/dev/usb2:/dev/ugen0

and scanimage found it on the third attempt:

# scanimage -L

No scanners were identified. ....
.
.
.

# scanimage -L
device `snapscan:libusb:/dev/usb2:/dev/ugen0' is a Acer FlatbedScanner42 flatbed scanner

after 6 attempts of:
# scanimage --quality-cal=no > image-7.ppm
scanimage: no SANE devices found

we got the scan:
# scanimage --quality-cal=no > image-7.ppm
#

and next:
# scanimage -L

No scanners were identified.....

And i have to wait several minutes getting this errors to get the next scan.

Case2: 
Benq 5000 powered on first time it is found by sane-find-scanner and scanimage successfully:

# sane-find-scanner -q
found USB scanner (vendor=0x04a5, product=0x20f8) at /dev/uscanner0

# scanimage -L
device `snapscan:/dev/uscanner0' is a Acer FlatbedScanner22 flatbed scanner

# scanimage --quality-cal=no > image-1.ppm
[snapscan] Scanner warming up - waiting 31 seconds.
#

OK. We got the scan.
After 3 minutes:

# scanimage --quality-cal=no > image-2.ppm

hangs forever...

If i kill scanimage and use sane-find-scanner:
# sane-find-scanner -q
# sane-find-scanner -q
.
.
.
i have nothing.


I would be very grateful if anybody points me on the root of this instability.
Thanks for your time!

-- 
Oleg