How To Determine Which Com Port A Device Is Connected To?

In the world of computers, peripherals like printers, scanners, digital cameras, and other USB devices are connected via ports. In order to communicate with these devices, the computer assigns each one a unique identification number called a COM Port. However, sometimes it becomes a challenge to determine which COM port a device is connected to. Knowing how to pinpoint the right port is crucial as it can save time and prevent errors while transferring data. In this article, we’ll explore how to determine which COM port a device is connected to and simplify the process.

One way to check for a particular device’s COM port is to use the Device Manager, which is a built-in tool for managing hardware on Windows computers. The Device Manager displays a list of the connected devices and the corresponding COM ports they’re using. For instance, to find the COM port for a USB printer, you can go to the Device Manager and expand the Ports (COM & LPT) option. From there, you can find out which port the particular printer is connected to. This is just one example; in essence, understanding how the Device Manager works is crucial in determining which COM port a device is connected to.

How to Determine Which COM Port a Device is Connected to?

When working with devices that communicate through a COM port, it is necessary to know which port the device is connected to in order to be able to communicate with it. There are several ways you can determine which COM port a device is connected to:

1. Check the device manager: In Windows, you can open the Device Manager and look for the device in question. Once you find the device, you can check its properties to see which COM port it is using.

2. Use a serial port scanner: There are several third-party serial port scanners available that can scan your system and identify connected devices and their COM port numbers.

3. Use a diagnostic tool: Some device manufacturers provide diagnostic tools that can be used to identify devices connected to a COM port.

4. Try different ports: If you are not sure which port a device is connected to, you can try connecting it to different ports and checking which one it appears on.

5. Check the device manual: The device manual may provide information on which COM port the device is designed to connect to.

6. Use command prompt: Open the command prompt and enter the “mode” command, followed by the port number you want to check. This will display information about the specified port, including the device connected to it.


1. What is a COM port?
A COM port is a serial communication interface used to connect devices, such as printers, scanners, and modems, to a computer.

2. How do I determine which COM port my device is connected to?
You can determine which COM port your device is connected to by opening the Device Manager in Windows, expanding the Ports (COM & LPT) list, and looking for the device name.

3. Can I use command prompt to determine the COM port of a device?
Yes, you can use the command prompt to determine the COM port of a device by typing “mode” followed by the device name in the command prompt window.

4. What should I do if I can’t find my device in the Ports list?
If you can’t find your device in the Ports list, try unplugging and replugging the device, and check if it appears in the list. If it still doesn’t appear, your device may not be recognized by your computer.

5. Is it possible to change the COM port number of a device?
Yes, it is possible to change the COM port number of a device by going to the Properties of the device in the Device Manager and selecting the Port Settings tab. From there, you can select a different COM port number.


In summary, determining which COM port a device is connected to can be a simple process with the right tools. By following the steps we have outlined in this article, you should be able to easily identify the correct port and establish a connection with your device. Remember to check your device’s documentation for any specific instructions, and always be sure to use caution when making changes to your system’s configuration. With these guidelines in mind, you should be well on your way to successfully connecting your device to your computer!

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