A2oz

How to Change COM Port Number?

Published in Hardware 3 mins read

Changing a COM port number can be done through various methods depending on your operating system and the device you want to modify. Here's a breakdown of the common approaches:

Windows:

  1. Device Manager:
    • Open the Device Manager by searching for it in the Start menu.
    • Find the device you want to change the COM port for (e.g., a modem, printer, or serial device).
    • Right-click the device and select Properties.
    • Navigate to the Port Settings tab.
    • Click the Advanced button.
    • In the COM Port Number dropdown, select the desired port number.
    • Click OK to save the changes.
  2. Registry Editor:
    • Open the Registry Editor by searching for regedit in the Start menu.
    • Navigate to the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\COM Name Arbiter.
    • Locate the entry corresponding to the device you want to modify.
    • Change the PortNumber value to the desired port number.
    • Close the Registry Editor and restart your computer.

Linux:

  1. udev rules:
    • Create a new file in the /etc/udev/rules.d/ directory.
    • Add the following line to the file, replacing DEVICE_ID with the device's ID and COM_PORT with the desired port number:
      SUBSYSTEM=="tty", ATTRS{idVendor}=="DEVICE_ID", SYMLINK+="ttyS%d" % {COM_PORT}
    • Save the file and restart the udev service.
  2. Serial port configuration:
    • Use the stty command to modify the port settings.
    • For example, to set the COM port number to 10:
      sudo stty -F /dev/ttyS0 speed 115200 -F /dev/ttyS10
    • Replace /dev/ttyS0 with the original port and /dev/ttyS10 with the desired port.

macOS:

  1. System Preferences:
    • Open System Preferences and navigate to Printers & Scanners.
    • Select the device you want to modify.
    • Click Options & Supplies.
    • In the Port section, select the desired COM port number.
    • Click OK to save the changes.

Note: The exact steps and options may vary slightly depending on the device and operating system you are using.

Practical Insights:

  • Changing COM port numbers can sometimes cause conflicts with other devices.
  • It's important to ensure that the new port number is not already in use by another device.
  • Always back up your system before making any significant changes to the registry or system files.

Examples:

  • If you're using a USB-to-serial adapter and want to change its COM port number to 10, you can follow the steps outlined above for Windows or Linux.
  • If you're using a printer connected to your computer via a serial port, you can change its COM port number to ensure it doesn't conflict with other devices.

Related Articles