Changing COM Port Numbers in Windows 7

When you install drivers for a new USB device, Windows may assign it a high COM port number. To change it to a lower number, follow these steps:

  1. Open Device Manager (for example, click Start, select Run, and enter devmgmt.msc).
    Open Device Manager.
  2. Right-click the device whose COM port number you want to change and select Properties. In this example, the OPTO-GAZ interface will be reassigned from COM5 to COM2.
    Open the properties of the OPTO-GAZ interface.
  3. Open the Port Settings tab and click Advanced.
    Open the COM Port Number list in Advanced Settings.
  4. Select the desired number from the COM Port Number drop-down list. Choose an available port, avoiding those marked “in use”. In this example, COM2 is available and will be assigned to the OPTO-GAZ interface.
    Select the available COM2 port.
  5. Click OK to confirm the change. COM5 will become available for another device, and COM2 will be assigned to the OPTO-GAZ interface.
    Confirm the change from COM5 to COM2.

Original guide by Radosław Podgórski. English translation and editorial adaptation.
Source: Podmienianie portów COM na podstawie Windows 7 . Illustrations are English-localized versions of the original screenshots.