Change port


Applies To: Windows Vista, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows 8

Lists or changes the COM port mappings to be compatible with MS-DOS applications.

For examples of how to use this command, see Examples.


In Windows Server 2008 R2, Terminal Services was renamed Remote Desktop Services. To find out what's new in the latest version, see What’s New in Remote Desktop Services in Windows Server 2012 in the Windows Server TechNet Library.


change port [<PortX>=<PortY> | /d <PortX> | /query]





Maps COM <PortX> to <PortY>.

/d <PortX>

Deletes the mapping for COM <PortX>.


Displays the current port mappings.


Displays help at the command prompt.


  • Most MS-DOS applications support only COM1 through COM4 serial ports. The change port command maps a serial port to a different port number, allowing applications that do not support high-numbered COM ports to access the serial port. Remapping works only for the current session and is not retained if you log off from a session and then log on again.

  • Use change port without any parameters to display the available COM ports and their current mappings.


  • To map COM12 to COM1 for use by an MS-DOS-based application, type:

    change port com12=com1
  • To display the current port mappings, type:

    change port /query

Additional references

Command-Line Syntax Key


Remote Desktop Services (Terminal Services) Command Reference