Add serial device in Windows 11

Topic

I need to add an external modem attached to COM1 in Windows 11. The device is known (in Windows 10) as “Standard 14400 bps modem”. This was easy in Windows 10, but seems difficult in Windows 11. Windows 11 seems entirely happy with a COM port on COM1. I can use the command line to send to send data to the modem (causing indicator lights to change). Is there some voodoo, or does Windows 11 no longer support serial devices (modems, printers, etc)? Thanks in advance.

Replies

You have a driver for that device that emulates a COM port. That driver may not work in W11 – check the manufacturer’s web site.

cheers, Paul

p.s. what is the device?

Up until two years ago, I used a Radio Shack USB -> DB9 RS232 device with Win10. It required a driver supplied with the device. There were several versions of the driver available and I had to try each till I found the one that worked. I also had to configure the COM port.

I have not had the opportunity to use it with Win11, BUT, I suspect I would not be able to because finding a Win11 driver for an old adapter made by a long defunct company is probably not realistic. The adaptor you choose to connect should have drivers that are Win11 compatible.

Thanks for getting back to me.

The system is a Dell Optiplex, and it has a physical DB-9 RS-232 port, seen under Windows 11.

In case someone has the same question: I spent some more time searching and reading. Turns out that adding an external serial modem is not “adding a device” in windows 11; it’s “adding a legacy device”. Makes a significant difference in the search results. Open up device manager, select the computer name, pull down the Action menu, and there it is “Add legacy hardware”.

Note: on first opening device manager, the Action menu only shows Help. You need to select the computer name before the Action menu shows more choices.