I am developing software for scanning using Twain 2.3.
This software has cases where need stop scanning.
I’m using “DG_CONTROL / DAT_PENDINGXFERS / MSG_STOPFEEDER” to stop scanning.
In Windows 8 it works great. Scanner scans 3 pages after stop command and stops.
In Windows 7 it doesn’t work. Scanner always scans all batch.
You need to contact your scanner vendor for help with this kind of problem. The TWAIN Working Group handle the Specification and the Data Source Manager, but the actually TWAIN drivers are written and maintained by each scanner vendor.