[sane-devel] Looking to add support for Avision AV50F plus scanner

[m. allan noah]

Something of note is that most Avision scanners are fundamentally
SCSI-over-USB, which means you can gain some understanding of the API
structure by looking at the SCSI scanner spec. You should be able to find
that with a google search.

allan

On Wed, Sep 4, 2024 at 10:13 AM Ralph Little <skelband at gmail.com> wrote:

> Hi,
>
> On Wed, Sep 4, 2024 at 6:28 AM Ove Laurum <laurum.tech at gmail.com> wrote:
>
>> Hello and thanks for your responses.
>>
>> The effort does not dissuade me, it will have to take the time it takes,
>> in the meantime I will just have to retain a windows VM for using the
>> scanner.
>> ...
>> Ralph, I was trying to find where the source code is, GIT hub? or
>> somewhere else? so that I can take a look at the code for some examples of
>> backends. I assume it's written in C.
>> I found
>> https://www.commandlinux.com/man-page/man-page/man-page/man5/sane-avision.5.html
>>
>> So I will start there trying to figure out how to read logs for the
>> scanner as per your suggestion.
>>
>>
> The SANE project is hosted at Gitlab, and you can find the source and
> currently reported issues here: https://gitlab.com/sane-project/backends
> The main website is here: http://www.sane-project.org/
>
> The SANE code is divided up into two main repositories: backends and
> frontends. You will find the backends contain all the code required to talk
> to scanners.
> Best way to start is to clone the backends repository and build it. On
> Linux, building is fairly straightforward and there are instructions in the
> INSTALL file.
>
> If you wish to generate a log file from a backend, each backenc man page
> does indeed contain instructions, but broadly each backend has its own
> environment variable that can be used to get debug messages at various
> numerical levels. One example might be:
>
> SANE_DEBUG_AVISION=50 scanimage -d {your device} {other parameters etc}
>
> Consult the man page (man sane-avision) for details as to what level of
> diag corresponds to which number.
>
> Personally, I would start with the avision backend. Many Avision devices
> use the protocol that is supported by that backend but it is not guaranteed
> in your case.
> The backends are designed to support specific protocols and often these
> protocols are shared amongst different manufacturers. Some scanners use
> scanner-on-a-chip hardware (for example from Genesys) so a backend may
> support a wide range of devices from different manufacturers. In other
> cases, they are more manufacturer specific (like Canon with the pixma
> backend for example).
>
>
>> The other thing I will have to do is to trace a successful scan operation
>> on Windows.
>> My goto tracer would be wireshark, I know I can trace USB ports in Linux
>> so I assume that is possible on Windows as well to get a trace of
>> successful scanning.
>> But is there a better tool to trace the USB traffic on Windows for the
>> purpose of establishing some form of API?
>>
>>
> Yes, we would usually do a scan on Windows and capture it using Wireshark.
> I don't know of any particular analysis tools that could help you here. The
> ones I have looked at I tend to print out and mark out with pen. Pretty old
> school. If this device is supported by the avision backend, then I would
> suspect that initial communications are pretty generic and get a little
> more specific later on. On communications that I have seen, the early USB
> exchanges establish the devices type and capabilities. The result of this
> early exchange is output in the diag stream so would be a good place to
> start.
>
> I don't know the backend very well, but I probably would start with the
> sane-avision man page and look into how to add the USB ids of your device
> to the backend's code or config file and just give it a try, capturing some
> detailed diag output. I would then study a trace gotten from a Windows scan
> to see how to go from there. If you are stuck at this point, I can spend a
> little time reminding myself how that backend works and help you out.
>
> There is a bit of a steep learning curve and each backend has its own way
> of doing things. Different scanners can have a completely different way of
> working, some are fairly high level like avision and pixma, while others
> are very low-level like genesys or rts8891.
>
> Cheers,
> Ralph
>


-- 
"well, I stand up next to a mountain- and I chop it down with the edge of
my hand"
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