COM Port on Windows 10 - Common Problems

Check COM Ports in the Device Manager

The Device Manager is the easiest way to see the list of your available ports. Generally, if you want to inspect your PC’s components, it’s the first place to look. There are multiple ways to open the Device Manager to see Windows 10 COM ports:

• Press Win+X, and select it from the newly opened menu.

• Press Win+R to open the Run prompt, and type in devmgmt.msc.

• Simply type “Device” into the search bar, and find it in the search results.

If you have problems with COM ports not showing in Device Manager, this could be caused by a different version of Windows that hides them by default, a technical issue with your motherboard, or a lack of drivers for a USB-to-serial adapter.

How to Find COM Ports on Windows 10

1. Open the Device Manager.

2. Optionally, enable “View” → “Show Hidden Devices”.

3. Locate “Ports (COM and LPT)”.

You can now right-click any individual port to view their Windows 10 COM port settings, and possibly disable them or update their drivers.

List COM Ports - Windows 10 Command Line Solution

If you’d want to know how to view COM ports in Windows 10 through the Command Prompt, it’s easy, but first you need to launch CMD. This is done by entering “cmd” in the Run prompt, which is opened with Win+R.

Once the terminal is opened, type mode and confirm by pressing Enter. You will get data on the available ports and their settings.

Some details on how to check COM port in Windows 11 are different, since the addition of the Windows Terminal.

What Port Am I Using?

COM ports are simple - unlike USB, the devices won’t identify themselves. Thus, the only way to see if anything is connected to a Windows 10 COM port is to receive a message from the connected device. This can be done with PowerShell. Before trying this approach, you’ll need to find the correct settings to be used when communicating with the device, including the baud rate, parity bits, etc.

How to Find what COM Port a Device is On

1. Open PowerShell by pressing Win+X and selecting “Windows PowerShell (Admin)”.

2. Add the port as an object:
   $port = New-Object System.IO.Ports.SerialPort [port name],[baud rate],[parity],[data bits],[stop bits]
3. Open the port with the $port.Open() command.

4. You can now read a single line from the port or send a message to it by running $port.WriteLine() or $port.ReadLine().

ReadLine will keep running until it receives one line of data. If you want to read from the port continuously, this is best done with a serial terminal application.