Unable to enumerate com ports in Windows 7

I’m working with 2 Digi Neo 8 cards in PCIe slots in Windows 7.

These cards were working fine but I was getting a BSOD on shutdown (an issue addressed in the 9.3 update). Card 1 had COM ports 3-10 and Card 2 had COM ports 11-18.

I’ve updated drivers from version 8.1 to 9.3, but the COM ports are now numbering from 61+

I’ve tried to renumber the ports (which I’ve done successfully in the past) to have card 1 start at COM3 again, but I get the error:

“The selected range for COM number enumeration is not available. Click Yes to allow setup to use the next available numbers, click No to select another starting COM number.”

How does the Digi ‘Advanced’ tab know what the next available number is? How do I avoid this and get back to the numbering I had before?


I believe the Windows registry is checked to see what COM port numbers are available to use.

Are you saying that you can’t ignore that message and force the COM port numbers that you want to use? If so, your Windows registry is probably corrupt with regards to COM port numbers, and this can be easily fixed (see the KB article linked below).


Does this help?

I’ve had a lot of trouble upgrading a couple of computers from 8.1 to 9.3 on Windows 7, especially when there are two Digi Neo 8 devices present.

Usually the first card upgrades fine (the Ports actually are still using the 8.1 driver, though) and when I upgrade the second card, I get a blue screen. On reboot the two cards are using different driver versions (the first upgraded card has 9.3 and the second has 8.1). Upgrading the second card, it will complete, but now the COM ports are numbered much higher than desired.

Now that I understand these high-numbered COM ports are related to the phantom COM port issue, I can correct it using the Digi Knowledge Base article. This has been successful in every case.

Typically I will then need to right-click and ‘Upgrade’ each COM port in Device Manager as the ports do not pick up the updated driver version.