Scanner not recognized when 'optimized' virtual channel is used. Below articles were already implemented to configure Generic USB redirection:

http://support.citrix.com/article/CTX123015

http://support.citrix.com/article/CTX137939

Configured the automatic Generic USB redirection of TWAIN device with the below steps:

>Verify on the client below is enabled:

32 bit OS:
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\GenericUSB\Devices] 
"AutoRedirectImage"=dword: 1  (Decimal)
 
64 bit OS:
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432 Node\Citrix\ICA Client\GenericUSB\Devices] 
"AutoRedirectImage"=dword: 1  (Decimal)


> In the Studio, configure the existing or create a new policy TWAIN Devices > Client TWAIN device redirection > (Set to Prohibited)
Default is Allowed . This would stop virtual channel redirection for TWAIN device only.
​
>To configure automatic redirection navigate to HKLM\Software\Wow6432Node\Citrix\ICA Client

Create a new Key: “USB”. Inside USB, create the following entries:

ExistingDevices (REG_SZ) = Always
NewDevices (REG_SZ) = Always
ShowAllDevices (REG_DWORD) = 1

>If these steps don’t help either then on existing configuration edit the policy and configure the below changes at user configuration:




Please ensure that on the endpoints you are not attaching the Scanner to a USB 3.0 port. As XenDesktop does not support Generic USB Redirection of devices connected to USB 3.0 ports. XenDesktop supports use of optimized virtual channels with USB 3.0 devices and USB 3.0 ports.
 

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Problem Cause

Virtual channels not disabled completely. Additional configuration needed to disabled virtual channel.