Com port number / IRQ number for DOS not staying the same after restart.

Posted on 2007-10-05
Last Modified: 2013-12-11
I have a customer that has a DOS aplication that prints directly to the com port ( and COM2 is hard coded into the application)
The computer's com port under device maniger shows the port as COM2, but under DOS it shows COM1 ( when using MODE command)
In order to get DOS to see the COM port as COM2, the user has to go into device maniger and change the settings, change it back, and the use the program in question.

Every time the computer starts up, it the com port under dos shows COM1, until it is changed manually by the user.

Can the com port be re-directed (or the IRQ changed from the command line ?)
Question by:Xorb
    LVL 32

    Assisted Solution

    Check motherboard BIOS settings (provided it's an integrated serial port). Usual BIOS default is Auto. Set serial port to COM2/IRQ3 in BIOS.
    LVL 20

    Assisted Solution

    Other things to consider:
    -check if the serial port COM2 is in use by internal dial-up modem and if so
    either disable modem or configure it to use COM1.
    LVL 5

    Accepted Solution

    Boot to Safe Mode
    Remove the drivers for all the COM ports in Device Manager, reboot to normal mode.
    LVL 2

    Author Comment

    Hi Guys
    Sorry I took so long to get back.

    Tried all of the sugestions, but the problem is still there. However, the need to solve this problem has now gone, since the device that was attached to that port (printer) has now broken down, and all replacement models are USB. The old software is being re-developed into a access database.

    I'm splitting the points between everyone that tried to help.

    Thanks for your time.

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