With serial port redirection, users can redirect locally connected, serial (COM) ports such as built-in RS232 ports or USB to Serial adapters. Devices such as printers, bar code readers, and other serial devices can be connected to these ports and used in the remote desktops and published applications.

After you install Horizon Agent and set up the serial port redirection feature, the feature can work on your remote desktops and published applications without further configuration. For example, COM1 on the local client system is redirected as COM1 on the remote desktop, and COM2 is redirected as COM2, unless a COM port already exists on the remote desktop. If so, the COM port is mapped to avoid conflicts. For example, if COM1 and COM2 already exist on the remote desktop, COM1 on the client is mapped to COM3 by default. You do not have to configure the COM ports or install device drivers on the remote desktops.

To make a redirected COM port active, a user selects the Connect option from the menu on the serial port tool tray icon during a desktop session. A user can also set a COM port device to connect automatically whenever the user connects to the remote desktop or published application. See User Operation of Serial Port Redirection.

You can configure group policy settings to change the default configuration. For example, you can lock the settings so that users cannot change the COM port mappings or properties. You can also set a policy to disable or enable the feature altogether. With an ADMX template file, you can install serial port redirection group policy settings in Active Directory or on individual machines. See Configuring Serial Port Redirection Group Policy Settings.

In VMware Horizon version 2103 and later, you can run a console utility vmwsprrdctl.exe on Horizon Agent to see a list of redirected COM ports. For every virtual COM port on the agent where the source port (remote COM port) on the client is created from a USB device, the utility provides the following information:
  • Hardware ID
    • USB device VID (Vendor ID)
    • USB device PID (Product ID)
    • USB device Rev (Product Revision)
  • COM port device description as it appears in Device Manager
For all ports, the utility provides the following additional information:
  • Source COM port number on the client side
  • COM port redirection status

The utility on Horizon Agent is in C:\Program Files\Common Files\VMware\SerialPortRedirection\Agent\vmwsprrdctl.exe.

For command line usage help for the utility, launch a desktop session in Horizon Client, and type:

# cd "C:\Program Files\Common Files\VMware\SerialPortRedirection\Agent\" (If the path is in the agent OS PATH environment variable, skip this step.)

# vmwsprrdctl.exe -h

This utility is supported on remote desktops and nested mode sessions on Windows client systems.

When a redirected COM port is opened and in use on a remote desktop or published application, you cannot access the port on the local computer. Conversely, when a COM port is in use on the local computer, you cannot access the port on the remote desktop or published application.