Question

COM port not found.

Asked by: bparnes

The object of our attention is an NT4 Server running SP5. Up until a week ago it was happily using the USR External Courier V.everything modem on its COM2 port. Then in the middle of the day while users were just doing ordinary tasks (no installs, crashes, shutdowns, etc.) the computer failed to establish communication with the modem. If I fire up Hyperterminal and try to connect to any destination, NT responds with COM2 NOT FOUND. The same happens regardless of the communications program I try to use.

I have done the following. I have tested the modem on a different computer and it works fine. I have checked the cable as well. I have tried a different modem on the COM2 port. I have booted the server to DOS and run both a COM port diagnostic and a modem diagnostic. Both programs affirm that COM2 is functional, that the modem is attached to COM2, and that the modem can be reached through COM2. I have uninstalled and reinstalled the modem using the latest driver obtained from the 3COM site. I have uninstalled and reinstalled the COM2 port using the PORTS control panel (with the default the base address and IRQ that are set in the BIOS). The modem service is set to manual.

However, if I use the modem control panel and tell the server to detect the modem, the detection simply hangs. The hourglass appears, but never disappears. I can stll get to other applications on the server though while the detection hangs. As I said previously, any application that needs to use the modem won't work, and fails to establish communication through COM2.

My question by now should be obvious. Does anyone have any idea about what else I can try to get COM2 recognized by the NT server, and communication established with the external modem?

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Asked On
2000-01-14 at 22:00:26ID10259788
Tags

found

,

port

,

com

Topic

Windows NT Operating System

Participating Experts
4
Points
200
Comments
6

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Answers

 

by: LermittePosted on 2000-01-15 at 02:38:48ID: 2355363

You can have two problems.

First problem is that the com-port is out of service, this means that it's broken.. You say also that you have already use a other modem on that port and that this don't work also. But that's not the cause. It's works under Dos..

Second problem, you have a IRQ confict. Go to the winmsd and see if you have a device with the same irq.If not try to change the Settings in the BIos and make it enable. Take Com4 and change it to the default setting 2E8. Did you see something in the events, from the day that the modem & Com port is down.
Then try to install the modem manualy, can you test this and come back..

Mario

 

by: bparnesPosted on 2000-01-15 at 06:37:45ID: 2355611

I won't have access to the computer again until Monday, so I can't give any test results until then.

If the COM port were truly broken, wouldn't tests of the COM port fail under DOS? When I test the COM port on the computer without NT in the way, the COM port and the modem test just fine.

As I remember, the events log is not reporting any IRQ conflicts. Also, the PORTS control panel is not reporting COM1, even though there is a mouse attached to COM1. Nor are there COM3 or COM4 (just COM2) in the PORTS control panel.

Thanks for you input. It really helps to have a sounding board for this problem.

 

by: TooKoolKrisPosted on 2000-01-15 at 09:43:44ID: 2355873

Default settings for COM1 & COM3 use IRQ 4 and COM2 & COM4 will use IRQ 3. When you have a serial mouse installed this will use a COM but will normally use IRQ 12.
     Take a look here to see if this can be of any help to you.

http://support.microsoft.com/support/kb/articles/Q161/5/16.asp

 

by: netmagePosted on 2000-01-15 at 18:09:42ID: 2356449


bpbarnes, this problem does look like a problem created by the VGA card taking the IRQ resource on boot.

This will not show up as a problem in DOS due to the VGA busmaster driver not activating until loaded by windows.

At first instance to try to fix this, in bios settings PNP, set irq 3 for legacy settings and turn "reset config data"on.
Turn "OS is PNP" off.
reboot
Look carefully at the bootup POST screen for the VGA card to check its not taking IRQ 3.

In NT control panel, check that COM2's resources are set to the irq 3 assignment.

 

by: bparnesPosted on 2000-01-16 at 19:42:18ID: 2358228

That was a helpful reference, TooKoolKris, but I'd already done all that before coming here. Still it was useful to know that I had covered all the standard stuff.

I will check for a conflict with the video adapter netmage. It does seem strange that such a conflict would develop in the middle of the day while the server was just doing its normal file and database serving.

Thanks again for all your comments.

 

by: SysExpertPosted on 2000-01-20 at 14:07:22ID: 2372461

Your comment about Com1 not showing up in the Ports control panel , may be the key to the problem.
I have had similar problems, and until all the com ports are properly defined in the ports section, NT will continue to ignore your modem.

Remove all the com ports and add them back with the standard definitions for IRQ/IO port. Make sure that the MB BIOS is setup the same way.

You should then remove the modem device and re-install it.

It is best to instal lit with a STANDARD MODEM setup first for testing it.

I hope this helps.

20120131-EE-VQP-002

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