Product Documentation

Enabling Scanners and Other TWAIN Devices

Jun 08, 2010

XenApp lets users control client-attached TWAIN imaging devices, such as scanners and cameras, from published applications. This feature is known as TWAIN redirection because XenApp provides TWAIN support by redirecting commands sent from a published application on the server to the client device.

Users can connect regardless of connection type. However, XenApp requires the following for TWAIN support:
  • The imaging device must be connected locally to the user device and have the associated vendor-supplied TWAIN driver installed locally.
  • Citrix online plug-in 11.x or later or the Citrix offline plug-in.
  • XenApp 32-bit and 64-bit servers support TWAIN redirection for 32-bit TWAIN applications only. XenApp does not support 16-bit TWAIN drivers.
  • The Client TWAIN device redirection policy setting must be added to the appropriate policy. To configure image compression, add the TWAIN compression level setting and select the appropriate compression level.
The following table lists the TWAIN hardware and software tested with XenApp. While other TWAIN devices may work, only those listed are supported.
Scanners and Scanning Devices Canon CanoScan 3200F
Canon CanoScan 8000F
Canon CanoScan LiDE600F
Fujitsu fi-6140
HP ScanJet 8250
Software Microsoft Office Publisher 2007
Microsoft Office Word 2007 Clip Organizer
OmniPage SE
Consider the following after enabling TWAIN redirection:
  • Configure bandwidth limits for image transfers. You can add the TWAIN device redirection bandwidth limit or the TWAIN device redirection bandwidth limit percent settings to the policy and enter the appropriate values denoting the maximum bandwidth allowed for image transfers.
  • Some applications are not Remote Desktop Session Host aware and look for Twain32.dll in the \Windows directory of the user profile (by default, C:\Documents and Settings\UserName\Windows). Copying Twain32.dll into the \Windows directory of each user profile resolves this issue. You can also correct this by adding the application to the Remote Desktop Session Host application compatibility list with the following two flags specified:
    • Windows application: 0x00000008
    • Do not substitute user Windows directory: 0x00000400
  • This feature supports the following modes of TWAIN information transfer:
    • Native
    • Buffered Memory (most scanning software works by default in Buffered Memory mode)
    Note: The disk file transfer mode is not supported.