I.R.I.S. Readiris 14 for Windows User Guide - Manual (Page 137)

How to
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Configuration

Click the down arrow beneath Scan in the ribbon.

Then click Settings.

When you do this for the first time, the Scanner Model list
appears automatically.
In this list you select your scanner profile. The scanner profiles
allow you to access features specific to your scanner. For
example, duplex scanning.
Do not worry if you don't see your scanner in the list; not all
scanners have specific scanner profiles.
Important note: in case you don't find the exact same profile, do
not select a profile that resembles it. Instead, select a universal
Twain profile. Different Twain profiles are available:
Select <Twain><OTHER MODELS> when you are using
a regular, flatbed scanner.
Select <Twain><OTHER MODELS>(User interface) if
you want to use your scanner user interface to scan
documents instead of Readiris.
Select <Twain><OTHER MODELS with duplex
feeder> when you are using a duplex scanner, which scans
both the front and backside of a page.