What app is using the Com Port?

Windows XP, service pack 2. An app trying to connect to a device on the com port reports that another app is using it. How can I determine what the other app is?

These days modems are usually the only things that use com ports.
You can check whether one is being used under Control Panel, Phone and Modem, then pick the Modem tab. It will tell you if there’s a Com port assigned to it.

Hope this helps:-)

Thanks, but there is no modem. I suspect it is a virtual comm port.

DO you have UPS (battery backup) power supply software installed?

Also; sometimes using COM1 will tie up COM3, COM2 ties up COM4, depending on software.

If I recall correctly, Process Explorer (which you can download from Microsoft) will tell you what files, dlls, devices, etc. all of your process are using.

Other than modems bluetooth drivers will virtualize com ports and older PDA IO software can tie up com ports. If the system is an older notebook that has infrared IO that can also use com ports.

I have nothing useful to add, but I just have to share that when I read the thread title, I originally thought it said “Corn Port.” And yes, I know what a com port is, so I don’t know why my brain processed it that way. I’m not sure I want to know what a corn port is…

Read Faulkner. Sanctuary.

Well I’ve just checked my Modem Options. I have one listed which is my Bluetooth device, on Port 14. I’m surprised it didn’t pick port 1,2 or 3. So as you suggest it must have created a virtual port:)

The question then, is why doesn’t your app do the same?:confused:

As already suggested by Mr Geek, Process Explorer may help you ascertain what is hogging your systems resources.

Do you have a firewall? I have a USB to Serial adapter for some software I am developing and my firewall would not allow me to open the port.

I didn’t find it by device, but a Company Name that I did not recognized proved to be it.