How to Change COM Port for a Device in Windows

Recently, I bought a Prolific USB-to-Serial adapter for flashing my Android smartphone that I had accidentally bricked. I found out the RXD, TXD and GND points on the mobile phone, connected them to the Prolific adapter, but the software refused to flash the mobile phone. The reason, that I figured out after many hours of hair pulling, was that the flashing software works only with COM 1, COM 2 and COM 3 while the Prolific USB-to-Serial adapter was selected automatically to use COM 11 in Windows. After changing the adapter port from COM 11 to COM 2, I was finally able to flash the mobile phone.

Some of the software are designed intentionally to work with a selected number of COM ports. In order to work with this type of software, you may have to change the COM port number for a connected device. Here is how you can change the COM port for any connected device in Windows:

  1. Connect the device for which you want to change the port to your PC. Let Windows detect the device. If the device is not PnP ready, then you may have to reboot the PC so that it is recognized.
  2. Press Win+R hotkey to open the Run dialog. In the Run dialog type devmgmt.msc and press Enter to open the Device Manager.
  3. In the Device Manager, you will be able to find the connected communication device under the Ports (COM & LPT). Select and right-click on the target device and choose Properties from the context-menu.Change COM Port in Windows
  4. In the Properties window, switch to the Port Settings tab and click on the Advanced button.Change COM Port in Windows
  5. In the Advanced Settings window that opens up, you can choose an available port number from the lower-left corner of the window. In the following screen shot, I have changed the port from COM 11 to COM 2.Change COM Port in Windows
  6. Click on the OK button to save the settings and close the open windows. You may have to remove and re-attach the device for the new settings to take effect.

Conclusion: If an application is not working because your device is not using a particular COM port number, then you can change the port number very easily in Windows. This is specially useful for older devices and applications that make use of the fewer number of COM ports.

4 thoughts on “How to Change COM Port for a Device in Windows

  1. I need to change a Prolific USB to serial port to COM 1 to operate a program. When I go to do this it says that COM 1 is in use and changing may cause some devices to operate improperly or be inaccessible. How do I find out what is using COM1? I checked all of the printers and they are not using COM 1.

    1. In the Device Manager, click View -> Show Hidden Devices. It will show you how COM1 is being used. It is hidden because a driver has been installed to use COM1 and the device has been removed.

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