drew
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TWAIN amnd serial protocol for digital camera
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Jun 12 17:53 UTC 1998 |
I am looking for information on the TWAIN standard for imaging
devices. I have a camera that is supposed to be TWAIN-compliant that
I want to write software for, to substitute for the bloatware that
came with it that's supposed to require Windoze 95 though it has
been running under NT. I'm figuring that this should be possible
since the interface is via a serial port, and the speed can be
adjusted from 115200 baud all the way down to 2400, which is easily
manageable by 8086-class computers running ProComm.
However, in order to do this, I need to find out the protocol
that is used in communicating. To wit, I need to know things like
what to send out the COM port to establish the connection, or download
an image, or change settings; and also, especially when downloading,
how to process the data that comes back. (Which bytes are data, where
is the checksum, etc.)
I have managed to find a bunch of TWAIN packages, including things
like TWAIN.DLL, TWAIN.H, and other software for development in C/C++,
plus a huge set of Word documents describing the requirements for TWAIN
and descriptions of functions with names like TWAIN_AcquireImageSource().
However, information as to the actual contents of the serial port
traffic still eludes me.
Similar information exists for other cameras (QV10 series and Kodak
DC20), but the closest I could get for mine (HP) is a few web pages
in Japanese for a Konica Q-EZ, which appears to be the same camera
under a different brand name; and they might not contain anything useful
even if I do manage to get them translated.
I *am* going to write to HP inquiring on this, telling them what I
want it for. However, I doubt that they will be cooperative. So, given
that the device is "TWAIN compliant", is there a single set of COM port
codes that can be counted on to work? Where should I look for such
information?
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scott
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response 1 of 3:
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Jun 12 22:37 UTC 1998 |
Don't know, but if you are comfortable programming for COM ports, you could
write a program that listens to a serial stream and saves the results for your
inspection. It's possible to have a serial output feed more than one input,
and at my office we have a DOS based software that listens to 2 ports for
bidirectional data, and displays the results. Paid for itself the first
time...
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drew
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response 2 of 3:
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Jun 13 22:38 UTC 1998 |
I have experimented with something like that, sending ground and data in or
out, depending on what I decide to monitor, to the COM port on the palmtop.
I believe I can eventually get enough data to piece together some command
codes, and perhaps tell the camera to send one or more thumbnails (which is
primarily what I want; I want to be able to check its contents "in the
field").
However, it occurred to me that the data sent back can take any of many
different forms, from an ordinary bitmap, to a JPEG file, to some wierd
compression scheme that I've never heard of before, to data with no headers
whatsoever. It could take years to go through and test all the possibilities
on the data recovered.
I would, however, be interested in hearing more about your COM monitor,
possibly for future projects.
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