LabVIEW
LabView Twain communication for flatbed scanners
Twain is a VERY old standard from the stone age of computing. It is very tricky to get right and its API is obscure to be able to be implemented with the technology available on computers from the begin of the 90ies of last century. While it still works under Windows, it is normally only used by high end document management software. The WIA (Windows Image Acquisition) API is the standard way to integrate scanners under Windows if you don't have advanced scanner features such as automatic paper feeders and similar. Windows provides also a WIA to Twain bridge so that any scanner manufacturer who provides a WIA driver for his devices, can still support Twain applications without having to develop a Twain driver themselves.
So if your scanner does not provide automatic document feeders and such, the standard way to access it under Windows is normally through the WIA API. The few applications that can handle scanner input usually make use of that API unless they are expensive professional document management systems which still often use the Twain API. The market for a LabVIEW Twain driver is however so small that it simply doesn't pay even for the cost of distribution and sales of the thing, not to talk about development, support and long term maintenance.
I'm pretty sure that WIA is in one way or the other accessible through .Net, Twain most likely too. But they usually are not free either.
I'll have to check about my old library, but am not sure how I could make it available. It was a hairy DLL to write and some of the internal message loop handling made me rather uneasy about if it would work in future Windows versions.
Indeed the WIA API is only really documented in the Windows DDK, which describes how to write a WIA driver for a device. From that one can deduce how to call the user space COM API that allows accessing WIA. I did dabble with that in the past to access USB still image cameras, but that is nowadays also already an almost obsolete feature.
As I said I have done a Twain library in the past but will need to assess if it still works in modern Windows systems, which is additionally made difficult by not having any scanner available to test with. This was in Windows 2000 times (yes very old), so I would be very surprised if it simply works with Windows 10 and LabVIEW 202x.
No I can't post it as is. I tried and it runs into some Windows problems that will need to be fixed in the associated DLL first. Also this has been very considerable work (several weeks of full time initial development and many more hours of maintenance and bug fixes as it got used in a few internal projects) that I could not post for free use. It is not accessing any ActiveX or .Net component, but directly the Twain Data Source Manager, but was developed for the Twain standard 1.8. The current version 2.4.3 that is released by the Twain Group does use different DLL names and possibly different APIs, so it will not work with the current DLL I have and installing an old Twain DSM 1.8 on modern Windows systems is not going to be a solution either.
I need to see what I can come up with for this but it is not working properly as is!
