For Twain scanning, a default twain device must be set via the RVI Socket Server interace.
The RVI Socket Server interface is automatically installed with the RVI PC Viewer. It is accessible through the Windows system tray. Right click the RVI Socket Server icon and select Settings.
If you do not see the RVI Socket Server icon in the system tray, manually start the socket server from
C:\Program Files (x86)\Real Vision Software, Inc\RVI Sockets\RVISockets.exe
TWAIN Device: The list of available TWAIN Devices is determined by the twain driver(s) installed on the pc.