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  1. Updated: March 26, 2025
    Published: March 26, 2025

Horizon Composite USB Splitting

Document Purpose

Some devices require USB redirection for specific USB interferfaces, but not others. This document will outline the process to identify the different USB interfaces, and how to configure a profile to redirect and split these devices into a Horizon session.

USB Splitting is only supported in Citrix and Horizon

At this time Microsoft RDS / RDP, Azure Virtual Desktop, and Amazon AWS do not support device splitting

Example Devices That May Need to Be Split

  • Dictation Microphones
  • Bloomberg Keyboards
  • USB Printer / Scanner Combinations

Required Access / Resources

  • For this process you will need the following items:
  • Root access to an IGEL or Linux-based endpoint
  • USB Device that needs to be split
    • If you need to connect the device then physical access may be required
  • Local Terminal / SSH / Secure Terminal Access

Additional Requirements for Some Users

Some devices, such as the Nuance PowerMic line of devices, require being connected and configured in gold image before deploying. You may need direct access to the Gold Image and the rights to install and initialize device drivers in the gold image before this will work.

Identifying USB Device Interfaces

In this article, I will be using a Nuance PowerMic III (Dictaphone) device as an example. In VWMare and more modern versions of Citrix (CWA 2206 and later) it is required to redirect the unidentified HID interfaces of these devices inot the session with USB redirection. However, you will not want to do this for the Audio interfaces, or HID devices that have a local Linux Driver. You will want these to be optimized by Horizon RTAV, Citrix HDX, or HID virtual channels.

Identifying Vendor ID (VID), Product ID (PID), and the Device Number

  1. Open a terminal and connect the device to the endpoint
  2. Run the lsusb command to generate a list of connected devices 
    lsusb
  3. Identify thedevice in the list, and make a note of the following items:
    • Bus Number
    • Device Number
    • Vendor ID (VID)
    • Product ID (PID)

lsusb command

Can't find the device in the list?

If you cannot identify the device by name, try unplugging the device, running lsusb, plugging it back in, and running lsusb again.

Compare the results and see which device(s) shows up when it is connected.

Identifying Device Interfaces

At this point, we can use the lsusb -t command to look up the available interfaces, but the default output can have a lot to sort through and we can narrow it down a bit.

Using the information collected in Identifying Vendor ID (VID), Product ID (PID), and the Device Number we will build a command to just return the interfaces for the device we are looking at. This will be formatted like below:

Example for PowerMic III, your device number will change. 

lsusb -t | grep "Dev 9"

Handling preceding zeros

You will need to remove any preceding zeros from the device number.

lsusb-t

Note the interface number and classes

At this time, you will want to note the interface numbers, and their corresponding classes.

Creating the corresponding IGEL Profiles

For our PowerMic III we will need to redirect the Human Interface Device (HID) interfaces and not the audio devices. In this section we will create a profile with default USB rules, and two

Horizon Client Profile

Horizon requires two rules to split USB devices. One that is set to "Allow" the device to be redirected, and a second to define the split. Horizon operates configures exclusions for interfaces, so in this case we will need be configuring the split rules to exclude the audio interfaces 0, 1, and 2.

Audio Optimization in Horizon

Horizon RTAV will need to be enabled in order for the audio to work with thie in place. You can enable RTAV in the Multimedia panel of the Horizon Global Settings in IGEL Profiles

Creating the Horizon IGEL Profile

  1. Create a new profile (or use your existing USB Redirection Profile if you already have one)
  2. Navigate to the following settings panel: Sessions -> Horizon Client -> Horizon Client Global -> USB Redirection
Fabulatech

If you are using Fabulatech then select Fabulatech USB Redirection*

  1. Set the Global Settings as the following for USB Redirection:
  2. USB Redirection - On
  3. Automatically connect at startup - Enabled
  4. Automatically connect when inserted - Enabled
  5. Default Rule - Deny

  6. Automatic splitting of composite USB devices - Enabled

  7. Create an "Allow" Device Rule using the Vendor ID and Product ID collected in the Identifying Vendor ID (VID), Product ID (PID), and the Device Number section

  8. Note: It's always a good idea to give your rule the name of device you are redirecting

  9. Create a second Device Rule to "Split" the device using the VID and PID, and the Interface IDs of the audio device collected in Identifying Device Interfaces with the following rules:

  10. Device Interfaces will always be two digits, if there is only 1 digit reported, then you will need to add a precediing zero
  11. Device interfaces should be seperated by a space vmware-split
Results

You should now have a profile that looks like the one below. vmware-complete-profile

References