Users can operate physical COM port devices that are connected to their client computers and use serial port virtualization to connect the devices to their remote desktops, where the devices are accessible to third-party applications.

  • After the Serial Port Redirection option is installed with Horizon Agent, a serial port tool tray icon ( Use the serial port icon to connect a serial port to the remote desktop ) is added to the remote desktop. For published applications, the icon is redirected to the local client computer.

    The icon appears only if you use the required versions of Horizon Agent and Horizon Client for Windows, and you connect over PCoIP. The icon does not appear if you connect to a remote desktop from a Mac, Linux, or mobile client.

    You can use the icon to configure options to connect, disconnect, and customize the mapped COM ports.

  • When you click the serial port icon, the Serial COM Redirection for VMware Horizon menu appears.
  • By default, the locally connected COM ports are mapped to corresponding COM ports on the remote desktop. For example: COM1 mapped to COM3. The mapped ports are not connected by default.
  • To use a mapped COM port, you must manually select the Connect option in the Serial COM Redirection for VMware Horizon menu, or the Autoconnect option must be set during a previous desktop session or by configuring a group policy setting. Autoconnect configures a mapped port to connect automatically when a remote desktop session is started.
  • When you select the Connect option, the redirected port is active. In the Device Manager in the guest operating system on the remote desktop, the redirected port is shown as Serial Port Redirector for VMware Horizon (COMn).

    When the COM port is connected, you can open the port in a third-party application, which can exchange data with the COM port device that is connected to the client machine. While a port is open in an application, you cannot disconnect the port in the Serial COM Redirection for VMware Horizon menu.

    Before you can disconnect the COM port, you must close the port in the application or close the application. You can then select the Disconnect option to disconnect the port and make the physical COM port available for use on the client machine.

  • In the Serial COM Redirection for VMware Horizon menu, you can right-click a redirected port to select the Port Properties command.

    In the COM Properties dialog box, you can configure a port to connect automatically when a remote desktop session is started, ignore the Data Set Ready (DSR) signal, enable the port to be a permanent port, and map the local port on the client to a different COM port on the remote desktop by selecting a port in the Custom port name drop-down menu.

    A remote desktop port might be shown as overlapped. For example, you might see COM1 (Overlapped). In this case, the virtual machine is configured with a COM port in the virtual hardware on the ESXi host. You can use a redirected port even when it is mapped to an overlapped port on the virtual machine. The virtual machine receives serial data through the port from the ESXi host or from the client system.

  • In the Device Manager in the guest operating system, you can use the Properties > Port Settings tab to configure settings for a redirected COM port. For example, you can set the default baud rate and data bits. However, the settings you configure in Device Manager are ignored if the application specifies the port settings.

For end-user instructions for operating redirected serial COM ports, see the VMware Horizon Client for Windows Installation and Setup Guide document.