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Citrix Virtual Apps and Desktops
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TWAIN Redirection

April 24, 2024
Contributed by: 
C

Introduction

TWAIN is a scanning protocol used to link image software to scanners or digital cameras.

How TWAIN works

  • Scan your documents using any of the 32-bit applications in your Citrix session.

    Note:

    Use a locally attached TWAIN-compliant scanner to scan the documents.

  • The Citrix scanning module redirects the TWAIN request to the client’s scanner.

  • Once the scan is complete, the session host is notified.

Requirements

Citrix Control Plane

  • Citrix Virtual Apps and Desktops 1912 or later
  • Citrix DaaS

Session Host

  • Operating system
    • Windows 10 1809 or later
    • Windows 11
    • Windows Server 2022 or later
  • VDA
    • Version 1912 or later
  • Application
    • 32-bit application

Client Device

  • Operating system
    • Windows 10 1809 or later
    • Windows 11
  • Workspace app
    • Windows: version 1912 or later
  • Scanner
    • TWAIN-compliant scanner

Configuration

  • Install TWAIN drivers on the client endpoint.

  • Set up devices or applications to select the required scanning protocol if they support both TWAIN and WIA.

  • Attach the scanner to the client endpoint locally (through USB).

  • Redirect TWAIN devices to the session via USB redirection if needed.

    Note:

    TWAIN devices don’t work well with USB redirection leading to poor scan quality.

Policy Settings

Policy settings to set up TWAIN redirection and improve scanning.

  • Client TWAIN device redirection: to enable or disable TWAIN redirection.

    Note:

    By default, TWAIN redirection is enabled.

  • TWAIN compression level: to set compression levels for images from client to host.

For more details, see TWAIN devices policy settings.

Troubleshooting

Try out TWAIN with the public test app Twacker, which can be downloaded from this URL.

Follow the steps to validate TWAIN within a published desktop session:

  1. Install Twacker on the VDA.
  2. Launch Twacker (32-bit version).
  3. Click File > Select Source and select your scanner from the list.
  4. Click File > Acquire.
  5. Click the Scan button to test your scanner.

If Twacker can scan successfully, it confirms that the Citrix Virtual Apps and Desktops setup is:

  • Configured for USB redirection
  • Using TWAIN devices
  • Meeting all local client device requirements

If you still have scanning issues within a particular application, then it’s likely to be a software issue.

TWAIN Redirection
April 24, 2024
Contributed by: 
C
April 24, 2024
Contributed by: 
C

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