Problem scan one page

I using Leadtools 16.5, with a scanner Canon 5010C and C#

I
would like to scan one page for a preview then scan all the other pages and save
them into files. For the preview  I set  TwanProperties.MaximumNumberOfPages to 1. But a TwainException is raided (Requiered capability not supported).
I can
prevent this exception by setting the TwainDuplexScanningMode to OnePass but I need it to be None.
Any ideas ?

Thanks you ,
Rémy

Hello Rémy,

The MaximumNumberOfPages is internally getting and setting the TransferCount (CAP_XFERCOUNT) capability of the Twain device. You could try setting this capability yourself to see if this will work as a work-around, but it may produce the same results. There is a small sample project here that will illustrate how you can do this:
http://support.leadtools.com/SupportPortal/CS/forums/30439/ShowPost.aspx

I would also suggest trying to use a tool from Twain.org called Twacker. To download Twacker, you can get it from http://www.twain.org/downloads.shtm within the Twain Developer Toolkit download. Try to set this capability via Twacker, and then test acquiring from the device. If the scanner has the same problem in Twacker, then the problem lies in the Twain driver and you should contact the manufacturer.

Could you also tell me what version of Leadtools.Twain.dll and Leadtools.dll do you have?

Thanks you for your reply, but I find my problem alone.

I have used for one page :
                                     twainProperties.MaximumNumberOfPages = 1;
                                     twainProperties.DuplexScanning = TwainDuplexScanningMode.OnePass;
And after acquire one page, I have used for to reset  :
                                    twainProperties.MaximumNumberOfPages = -1;
                                    twainSession.Properties = twainProperties;

I have used  for several page :
                                    twainProperties.MaximumNumberOfPages = -1;
                                    twainProperties.DuplexScanning = TwainDuplexScanningMode.TwoPass;

Rémy,

I've double checked our documentation on this, and the DuplexScanning property is a a read-only property. You're getting the "Required capability not supported" because this capability can't actually be set.

To work-around this, try setting the EnableDuplexScanning property on the TwainSession object to false. This should provide the same effect as having TwainDuplexScanningMode.None.