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

If a Horizon administrator has configured the serial port redirection feature, and if you use the VMware Blast display protocol or the PCoIP display protocol, serial port redirection works in the remote desktop without further configuration. For example, COM1 on the local client system is redirected as COM1 on the remote desktop. COM2 is redirected as COM2. If the COM port is already in use, it is mapped to avoid conflicts. For example, if COM1 and COM2 exist on the remote desktop, COM1 on the client system is mapped to COM3 by default.

You must have any required device drivers installed on the local client system, but you do not need to install the device drivers on the remote desktop. For example, if you use a USB-to-serial adapter that requires specific device drivers to work on your local client system, you must install those drivers, but only on the client system.

Important: If you are using a device that plugs in to a USB-to-serial adapter, do not connect the device from the Connect USB Device menu in Horizon Client. Doing so routes the device through USB redirection and bypasses the serial port redirection feature.

Tips for Using the Serial Port Redirection Feature

  • Click the serial port icon ( Use the serial port icon to connect a serial port to the remote desktop ) in the system tray or notification area of the remote desktop to connect, disconnect, or customize the mapped COM ports.

    When you click the serial port icon, the Serial COM Redirection for VMware Horizon context menu appears. If an administrator has locked the configuration, the items in the context menu are dimmed. The icon appears only if a Horizon administrator has configured the serial port redirection feature and all requirements are met. For more information, see System Requirements for Serial Port Redirection.

  • In the context menu, the port items are listed as port mapped to port, for example, COM1 mapped to COM3. The first port, which is COM1 in this example, is the physical port or the USB-to-serial adapter on the local client system. The second port, which is COM3 in this example, is the port used in the remote desktop.
  • To select the Port Properties command, right-click a COM port.

    In the COM Properties dialog box, you can configure a port to connect automatically when a remote desktop session is started, or you can ignore DSR (data-set-ready signal), which is required for some modems and other devices.

    You can also change the port number that the remote desktop uses. For example, if the COM1 port on the client system is mapped to COM3 in the remote desktop, but the application you are using requires COM1, you can change the port number to COM1. If COM1 exists in the remote desktop, you might see COM1 (Overlapped). You can still use this overlapped port. The remote desktop can receive serial data through the port from the server and also from the client system.

  • Connect to a mapped COM port before you attempt to start an application that requires access to the port. For example, right-click a COM port and select Connect to use the port in the remote desktop. When you start the application, the application opens the serial port.

    When a redirected COM port is opened and in use on a remote desktop, 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.

  • In the remote desktop, you can use the Windows Device Manager Port Settings tab to set the default Baud rate for a particular COM port. Use the same settings in the Windows Device Manager on the client system. The settings from this tab are used only if the application does not specify the port settings.
  • 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 command to disconnect and make the physical COM port available for use on the client computer.
  • If you configure a serial port to connect automatically, start an application that opens the serial port, and then disconnect and reconnect the remote desktop session, the auto-connect feature does not work. You also cannot connect by using the serial port's system tray icon's menu option. In most cases, the application can no longer use the serial port. You must stop the application, disconnect the remote desktop session, and reconnect again to resolve the problem.