Creating and using virtual serial (COMx) ports on NT

[hemanir]

Iam trying to create a virtual serial (COMx) port on NT 4.0, to install a modem.
Creating is fine, but when NT reboots, it checks for the physical existence of this port and deletes it. I know this from the event log. Something about "contents of latch register same as interrupt ..."
/fastdetect,/noserial mice boot options do not help.
Checked, double checked IRQ, port nos etc and they are all fine.
Anybody resolved this problem and how ?

Thanks,
-RSN

[BLEEHAM]

this came from Technet 12-99

Verify Your COM Port(s)
-----------------------

Verify that Windows NT recognizes your COM port(s) by double-clicking the Ports
icon in Control Panel to see if the COM port that the modem is connected to is
listed. If it is, Windows NT recognizes the COM port.

If the COM port is not recognized in the Control Panel Ports applet, there is
most likely a hardware problem or a configuration problem. Use the following
steps to troubleshoot the problem.

External Modems

1. If the COM port is on the motherboard or is provided by a serial card, make
sure the port is not disabled in the BIOS (also called the CMOS) setup of the
computer. Refer to the documentation for your computer to obtain information
about configuring options in the BIOS setup.

2. Make sure there are no other adapters or devices that are configured for the
same Base I/O Address or IRQ as the COM port to which the modem is attached.

3. Verify that the serial port is not defective. If the modem and any other
serial devices fail on the COM port but work on other COM ports, and you have
verified the two steps above, the serial port may be defective.

4. Verify the serial cable is not defective by using a new standard serial
cable.

Internal Modems

1. If the COM port is defined by an internal modem, make sure the jumpers on the
modem are configured properly. Internal modems will almost always have a
jumper on the adapter that configures the modem as a particular COM port.
There may or may not be jumpers that allow you to set the Base I/O Address
and IRQ to be used by the modem as well.

2. If the modem is configured for a COM port number that is assigned to a COM
port on the motherboard or a serial card (physical port), you must either set
the modem to use a different COM port, or use the BIOS setup to disable the
COM port with the same number as the internal modem. For example, if both the
internal modem and the physical COM port are set to COM1, you must either set
the internal modem to a different, unused COM port, or the physical COM1 port
must be disabled in the BIOS setup.

3. Make sure there are no other adapters or devices that are configured for the
same Base I/O Address or IRQ as the internal modem. Usually COM3, using an
IRQ (or interrupt) of 5, is a good choice for an internal modem. However, if
you have a sound card, you may need to choose a different IRQ than 5 since
many sound cards use that interrupt.

4. In the Ports component of Control Panel, verify that the IRQ settings and the
I/O addresses are correct. Check the System log with the Event Viewer for I/O
or IRQ conflict errors.

When possible, use standard settings for COM ports, which are as follows:

SERIAL 1 COM1: I/O Address = 3F8h IRQ = 4
SERIAL 2 COM2: I/O Address = 2F8h IRQ = 3
SERIAL 3 COM3: I/O Address = 3E8h, IRQ = 4
SERIAL 4 COM4: I/O Address = 2E8h, IRQ = 3

5. You do NOT need to add a new port in the Control Panel Ports applet to add
support for an internal modem. NTDETECT will detect the internal modem and
the COM port it is configured to use. If a duplicate port was added using the
Add button in the Control Panel Ports applet, use the Delete button to remove
the duplicate port.

6. Verify that the internal modem is not defective. Also, it is often a good
idea to check with the vendor of your modem to see if there is a flash
upgrade available for your modem.


HOPE THIS HELPS.

[dtiffany]

I had a similar problem with trying to get my modem to use COM3. Another user on this forum suggested I go to \i386\drivers\pcipnp.inf on the NT Workstation cd, right click on it and install. After a reboot, NT detected my modem and created COM3.