[sane-devel] Reverse engeneering of a network attached scanner?

[Jörg Knochen]

Hi!

I just bundled up a package containing the wireshark file, the resulting tif and a screen capture of the scanning process including the scan interface, wiresharks window and video of a webcam which shows the behaviour of the scanner in sync with the rest. I think it might be easier to work out the meaning of the data stream in conjunction with the video.

https://www.dropbox.com/s/oyfmmxcbi6qz55s/vistascan_package_140626.zip

What we can see:

• at frame 100 the scan is initiated in the imaging software
• at frame 135 the driver checks for the scanner
• at frame 220 the twain scan interface is open, the scanner starts its spindle
• at frame 413 the scanner opens its access door
• at frame 473 the access door recognises the plate and closes, pinching the plate
• at frame 500 the image plate is inserted (with quite some force, since it’s pinched in by the door)
• at frame 524 the scanner recognises the plate, starts pulling it in and switches on the erasing light (the plates can be reused, after being erased by photons)
• at frame 690 the fist usable data is coming in (look at the Twain GUI)
• at frame 1003 scanning stops, but the scanner has to pull the whole plate through it’s mechanism. Plates can have different sizes…
• at frame 1363 the plate drops out of the scanner
• at frame 1403 the light is turned off and the access door opens up again
• at frame 1559 the twain GUI is closed. the access door gets shut and the spindle gets turned off

you can see the inner workings of the scanner here:
http://www.duerrdental.com/en/products/imaging/vistascan-image-plate-scanner/vistascan-mini-plus/?changeLang=1

If there are any questions left… 

Jörg


On 25 Jun 2014, at 20:58, M. Allan Noah <kitno455 at gmail.com> wrote:

> The simplest, uncompressed bitmap.  
> 
> allan
> 
> Sent from my iPhone
> 
> On Jun 25, 2014, at 2:17 PM, Jörg Knochen <joerg at jcbone.de> wrote:
> 
>> Great!
>> 
>> So now I have to look into wireshark. As far as I can see, it writes a lot of different file formats. Which one would be preferable?
>> 
>> Thanks,
>> Jörg
>> 
>> 
>> On 25 Jun 2014, at 14:32, m. allan noah <kitno455 at gmail.com> wrote:
>> 
>>> This looks like a fun project! The complexity of a driver is often
>>> inversely proportional to the cost of the scanner. Since this is not a
>>> commodity machine, I'm not sure that rule applies. Take a wireshark
>>> dump of the smallest scan possible, and put it up on the web
>>> somewhere.
>>> 
>>> allan
>>> 
>>> On Wed, Jun 25, 2014 at 3:56 AM, Jörg Knochen <joerg at jcbone.de> wrote:
>>>> Hi!
>>>> 
>>>> I’m the administrator of a small dentists office. The IT is Macintosh based, with a FreeNAS Server, with one exeption: the workstation used for XRay operation has to run windows because of ONE missing twain driver for OS X.
>>>> 
>>>> The scanner is the following model:
>>>> 
>>>> http://www.duerrdental.com/en/products/imaging/vistascan-image-plate-scanner/vistascan-mini-plus/?changeLang=1
>>>> 
>>>> It can be attached by USB, but in our case it uses a network connection over IP.
>>>> 
>>>> If i could sniff this network connection and record the communication between the twain driver and the scanner - is there anyone out there willing to help me write a sane driver? The manufacturer has no interest so far in supporting anything but windows.
>>>> 
>>>> Another Idea: wouldn’t it be possible to install the original Twain driver into a wine bottle and write a sane driver which can pass through the twain commands from the bottle to a native interface on the unix side? This would be a GREAT workaround, too.
>>>> 
>>>> Thanks for your time,
>>>> Jörg-Ch. Knochen
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
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>>> 
>>> 
>>> 
>>> -- 
>>> "The truth is an offense, but not a sin"
>>