Lost TWAIN source on scanner

jeffowen

Member
I have been using my CanoScan 4200F on my Windows 7 64bit PC for a few years now without a problem.

I tried a scan today and I keep getting the message to say TWAIN source not found, check connections and restart the toolbox.

Nothing has been changed since I last used it about week ago, all the power and USB connections are OK. The scanner light comes on when the copy button is pressed, so the scanner software is linked OK to the scanner itself.
I have tried downloading the latest software including the TWAIN driver from Canon but this is no better. The only thing I have not done yet is to uninstall and reinstall. I don't see why I should have to do this, but may have to.
The only thing I know that has happened is the Microsoft updates a few days ago.
 

jeffowen

Member
Thanks Spirit, yes I have now done an uninstall and re install but with exact the same results!
I had a look at the printer/scanner display and did a troubleshoot on the scanner icon. The search said there was a problem but whether the info is any good I don't know. It said that the XML page could not be displayed.
 
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spirit

Moderator
Staff member
Seems very odd. Can you try the scanner with another computer and see if you get the issues?
 

jeffowen

Member
Well I plugged the scanner into my old XP machine and it worked just fine!

I have tried different USB cables into different sockets on my current Windows 7 machine and each time it says it can't find the TWAIN connection. It does seem strange that I push the COPY button on the scanner and the PC responds by bringing up the toolbar. To me this says that the communication is OK albeit one way.
Later today I will try and uninstall and re install it again.
 

jeffowen

Member
View attachment 6217This TWAIN problem is starting to annoy me. I have uninstalled and re-installed the scanner and its toolbox several times now and it still does not want to work.
Each time I get this message when I try to do a scan and now I don't know where else to look. As I have indicated I know the scanner works (on an XP machine), and it has worked on my Windows 7 machine a couple of weeks ago.
I tried to do a 'restore' to an earlier date (before Microsoft did an update) but even that fails.
Help please.
 
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jeffowen

Member
Have just installed the scanner into another Windows 7 64bit machine and it works OK!
That leaves my machine with the TWAIN problem. Any ideas?


2 hours later
I have come to the conclusion that during my uninstall process I am not completely getting rid of all the TWAIN features. My current question then is 'How do I get rid completely of all the scanner components before I reinstall?'


4 hours later
Continue to find answers and discover that I am not the only person that has this problem. One person suggested that I uninstall the scanner program and install it from the original CD-ROM in a virtual XP window (which I already have). I could install OK it but still no improvement!


It seems that properly uninstalling the program and all it's add ons may be the answer but I am loathe to pay 30 UK pounds for such a program and still not be sure it will work. Does any one know how to clear everything down without paying through the nose?
 
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spirit

Moderator
Staff member
Is this driver software really compatible with Windows 7? Are you using a driver that states it is specifically for Windows Vista/7? It's just that if it works in XP but not very well in 7 it makes me think it might not really be for 7.

I don't understand why uninstalling and reinstalling the program would cost you £30 when you already own it and why would driver software be charged for? Bit confused there.
 

jeffowen

Member
When I first got Windows 7 64bit pro I found that the only way to use my scanner was to download new drivers specifically for W7. The scanner worked OK for 2 years until last week when this TWAIN thing happened.

Since then I have tried all avenues to get it working again including reinstalling the recommended software for W7 but I believe that I am not completely uninstalling all the original software.
I don't know or brave enough to edit the registry where I think the problem lies so was recommended 'Perfect Uninstaller' which seemed to be doing a thorougher job but required $34 which, by the time Vat was added, turned out to be over £30. I decided that this was too much to pay.

I am sure the answer to the problem is simple if only I knew what it was.
 

jeffowen

Member
Thanks Spirit for the REVO Unistaller. I worked just fine as a unistaller but unfortunately it did not solve the problem.

Looking further on the web I found that many others have had the same issue and had solved it by adding the TWAIN details to the PATH. This is the site I found the details http://aaron-kelley.net/blog/2010/10/canon-scanner-error-cant-find-rmslantc-dll/

Looking in the Windows directory to find twain_32 I found my twain details were in CNQ4200. I then went to Control Panel>System then Advanced Settings then Environment Variables, I scrolled down in the window to select Path then Edit. I added to the right end of the detail ;%SystemRoot%\twain_32\CNQ4200

THIS WORKED! At last I have got my scanner working again. How or why this piece of data got lost I don't know but it's back now and all is OK.

Thanks to everyone who has helped.
 
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