Freeing up a COM port after a device removal 1

[Hobbes]

Hello everyone,
I'm using XP pro, SP1, and I'm attaching a number of USB devices (hubs and USB-Serial converters) to the system. The problem is, the control software I'm using needs me to specify the COM port for a given adapter. The only problem is when I go into Device Manager to change settings for the COM port (to match what I've already done for the other program), a number of COM ports are supposedly still being used when nothing is attached (say COM 2-8 locked up and 9-12 have something on them...).

Anyone know how to clear this up? I've tried pulling everything off the system and rebooting cleanly, but got bubkis from it.

Thanks in advance,
Scott

 

[linney]

See if these lead anywhere?


HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Ports

Search the Registry for COMn (n = number) and see what else you can turn up.

 

[Hobbes]

Thanks linney,
I found the ports listed in the ...\SOFTWARE\...\Ports line(The search for the ports basically all pointed me here...)

Should I just make a backup of the registry section and delete them?

Thanks again,
Scott

 

[linney]

It is always risky to experiment with the Registry, but if you decide to do so in an attempt to solve your problem then definitely back up any key prior to deletion.

The decision is yours. The only thing I can help you with is that you have a look at this freeware program and add it to your arsenal.

Registry Backup and Restore for Windows NT/2000/2003/XP

http://home.t-online.de/home/lars.hederer/erunt

 

[Hobbes]

Thanks for the tip.

I did the regedt32 deal, to no avail. These things are sticky. ButI did find out that they seem to be mapped to either the adapters or the hub ports (haven't done the leg work to figure it out yet, eyes too bleary...). So I don't know if this is a "real" problem or just a horrible inconvience. (probably a bit from column A and a bit from column B)

The software tip seems like a good one. It always helps to have more tools in the arsenal.

 

[bcastner]

Try:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;131976

 

[linney]

Following on from "Bcastner's" suggestion led to this to try.

/fastdetect:comnumber
This switch turns off serial and bus mouse detection in the Ntdetect.com file for the specified port. Use this switch if you have a component other than a mouse that is attached to a serial port during the startup process. For example, type /fastdetect:comnumber, where number is the number of the serial port. Ports may be separated with commas to turn off more than one port. If you use /fastdetect, and you do not specify a communications port, serial mouse detection is turned off on all communications ports.

Note In earlier versions of Windows, including Windows NT 4.0, this switch was named /noserialmice.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
131976 How to disable detection of devices on serial ports



833721 - Available switch options for the Windows XP and the Windows Server 2003 Boot.ini files

http://support.microsoft.com/default.aspx?scid=kb;en-us;833721&FR=1&PA=1&SD=HSCH