Compatibility Issues between HP TWAIN driver and NTWAIN open source library to acquire images

[Abhinavbpk]

Hello,

In my customized windows application (written in .NET and C#) , I am using NTWAIN open source library to acquire images from TWAIN device (my scanner).

In ADF mode, my application scans only one page even when there are multiple pages in the tray. 

The same code works with EPSON, KODAK and Fujitsu printers.

I have identified the code block in the NTWAIN which is not getting the expected value in case of HP.

The EndXfer command is giving pending count as 0 after the first page is scanned. pending count should be > 0 when there are more pages in the ADF tray.

session.DGControl.PendingXfers.EndXfer(pending);

Why HP TWAIN driver is not sending the correct pending count ?

The Twain driver version is 2.4 and I have downloaded the FULL version of the driver from the HP website.

Please suggest.

Thanks,

Abhinav

[Abhinavbpk]

Hello,

I printed all capabilities.
Out of all capabilities in the list, "ICapPhysicalHeight: 122" and "ICapFrames: L=0, T=0, R=8.5, B=122" caught my attention.
The page length is coming as 122 inches.
According to HP user manual, 8.5 by 122 inches is an Extra Long Page Size, and, "Only one page can be scanned when using a long or extra long page setting". I think this is why I am not able to scan more than one page.

I changed the page length through SupportedSizes = USLetter.
I again printed the list of all capabilities.
Now "ICapPhysicalHeight: 122" and "ICapFrames: L=0, T=0, R=8.266663, B=11.67999".
But still I am not able to scan more than one page.

If "ICapPhysicalHeight: 122" restricting me from scanning more than one page, why is HP Twain driver sending Physical width as 122 ?

Please suggest.

Thanks