How to tell what's using Com1

[mscj]

Running Windows XP--Com1 is not listed in the devices screen, but when
trying to renumber Com2 to Com1, properties shows Com1 is use.....how
can I tell what's using it?? Thanks-

 

[Guest]

renumber Com2 to Com1? never heard of such a thing!!
usually mouse or keybrd, not sure.
sometimes com 2 is reserved for external serial port>

trying to get a modem to work?

 

[mscj]

I've got a weather station that connects to the physical com port on
the motherboard--seemed to work ok when it was named COM1--now that
it's only showing a COM2, the weather station won't connect.......I
thought COM1 was always the physical serial port on the
board........can't figure out why the device manager shows COM1 in use.

 

[Guest]

Any ideas why it would change from Com 1 to Com2?
Is Com 2 enabled in your BIOS?
Does Com 2 show up under Ports in Dev Mgr?

 

[Robert Roland]

Running Windows XP--Com1 is not listed in the devices screen, but when
trying to renumber Com2 to Com1, properties shows Com1 is use.....how
can I tell what's using it?? Thanks-

It may be registered as a "Nonpresent device". Try this:

In a command prompt window, enter these two lines:

DEVMGR_SHOW_NONPRESENT_DEVICES=1
devmgmt.msc

The Device Manager should start. Select View and "Show hidden
devices". See if your com port has shown up. If it has, you can simply
remove it.

 

[mscj]

no com1 under hidden devices in device manager--com2 does show in
device manager--nothing on com1 at all. Under advanced settings for
com2, if I click the drop down for com port number, com1 and com3 have
"(in use)" beside them.........

 

[Steve Shattuck]

I've got a weather station that connects to the physical com port on
the motherboard--seemed to work ok when it was named COM1--now that
it's only showing a COM2, the weather station won't connect.......I
thought COM1 was always the physical serial port on the
board........can't figure out why the device manager shows COM1 in use.

First of all, com port names are arbitrary. In the good old days before
plug & play, DOS always assumed 2 serial hardware ports on the MB, and
assigned the COM1 & COM2 with corresponding addresses and IRQ's. The result
was trying to get COM3 and up to work because you ran out of IRQ's and DOS
couldn't share them easily.

Along come Windows and P&P, and now the OS shares IRQ's, assigns COM ports
in the sequence that it finds them, and thus many older programs that try to
use the old DOS conventions (like your weather station) frequently do not
work. Since you say it worked before, something has obviously changed.
Since there is no COM 1 listed in your Device Manager, some thought come to
mind.

1. Your MB ports are not designated correctly in the BIOS.
2. XP has assigned you COM1 to your modem, and modem ports don't appear in
Device Manager.

Make sure both COM ports are enabled in your BIOS, reboot. If that doesn't
do anything, delete you com ports and modem in the device manager and let XP
discover them when you reboot.

 

[Guest]

under com 2 adv
i have com 1 and com 4 in use.
com 4 is my modem

under modem adv.
com 1 and com 2 in use.

I have nothing connected to com 2. merely assigned to external MB serial/com
port.

like I said. com 1 is keybrd or mouse.


can you configure/assign com port usage in weather program?

 

[Bob I]

Perhaps someone/something messed with the BOOT.INI and removed
"/FASTDETECT" and if it's missing fix it.

Available switch options for the Windows XP and the Windows Server 2003
Boot.ini files
http://support.microsoft.com/kb/833721/en-us

 

[Robert Roland]

DEVMGR_SHOW_NONPRESENT_DEVICES=1
devmgmt.msc

I made a mistake. Should be:

SET DEVMGR_SHOW_NONPRESENT_DEVICES=1
devmgmt.msc

 

[Robert Roland]

no com1 under hidden devices in device manager

I made a mistake in my previous post. Please try again, using these
commands:

SET DEVMGR_SHOW_NONPRESENT_DEVICES=1
devmgmt.msc

To check if it worked, look under "Sound, video and game controllers".
There should be a few nonpresent devices there by default.