IF scanner is not connected to computer…

[davidyantz]

Hello everyone.

If I try to use MSG_OPENDS option while scanner is not physically connected to the computer’s usb port, a windowed error occures like this:

“Perhaps device is not connected properly. Check if device cable disconnected”.

I use ScanGear for Canon Lide series scanner. I think twain_32.dll does not bring up this dialog because I coudn’t find any matching strings like above within it’s executable body. So, I’ve decided that ScanGear itself raises that dialog (ScanGear has many-many files contained, and I was too lazy to find that error string within them)

And here comes question: how with the use of twain_32.dll I can detect this erroneous situation? Can I exactly be sure scanner is physically connected to the computer?

Thanks a lot

[gabe]

simple answer: you can’t
workaround/solution: you write a boxeater that watches for the known dialog (you know the text + you know the button ~= you know the dialog) and send the known response to the dialog.
drawbacks: it’s lame. (but it does work…)

slightly more complex answer that looks better in the beginning but proves to be useless across more vendors: there is a capability in the twain spec to see if the device is online ( search the forum and/or the spec for ‘online’) but with 99.72% of the devices I’ve tested it with it doesn’t do any good.

write a boxeater.

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[gabe]

and yeah – it’s the driver not twain_32 popping(pooping?) that dialog on you

solution #2: write the device vendor and your congressman, tell them you don’t like the dialog. sometimes they have another driver. a brilliant example is that most Hp scanners have another driver on the Cd with either the world “commercial” or “minimal” in the name. Those driver play much nicer with twain.

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[davidyantz]

Thanks for help, gabe.

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