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How do I swap the Com 1 and Com 2 assignments?

Anonymous
2012-08-01T16:05:21+00:00

I built two win7/32 systems using the same model intel motherboard. The boards have two com ports, a db9 and a pin header. My problem is that the com port numbers are reversed between the boards, e.g. the db9 connector on one board is com 1 but is com 2 on the other board. Intel tells me this is a Microsoft problem. I have tried to swap com 1 and com 2 in Device Manager but the swap doesn't survive a reboot. How can I do this?

Windows for home | Previous Windows versions | Devices and drivers

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  1. Anonymous
    2012-08-02T16:13:46+00:00

    I think I finally got it in Device Manager. The trick seems to be to do it in stages with a restart in between. Move Com2 to a whole other address/IRQ, restart, move Com1 to Com2's old address and restart. After the restart Com2 can be moved to Com1's old address and then the swapped assignments will stick without conflict.

    Thanks for your suggestions Tom, unfortunately you are a lot smarter than my BIOS which only does a global enable/disable for the ports.

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  1. Anonymous
    2012-08-01T22:03:53+00:00

    I can swap them in Device Manager so then:

    Machine A (default assignment):

    • Com1, IRQ 4, address: 3F8
    • Com2, IRQ 3, address: 2F8

    Machine B (swapped):

    • Com1, IRQ 3, address: 2F8
    • Com2, IRQ 4, address: 3F8

    but several times Com 1 on "B" has reverted to  IRQ 4, address: 3F8  in conflict with Com2.

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  2. Anonymous
    2012-08-01T17:40:18+00:00

    Check the BIOS again. These are the usual settings:

    Typical settings for Com ports are:

    • Com1, IRQ 4, address: 3F8
    • Com2, IRQ 3, address: 2F8
    • Com3, IRQ 4, address: 3E8
    • Com4, IRQ 3, address: 2E8

    Tom Ferguson

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  3. Anonymous
    2012-08-01T16:56:53+00:00

    The BIOS does not have that option :(

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  4. Anonymous
    2012-08-01T16:36:56+00:00

    Check the settings in the BIOS and reassign there.

    Tom Ferguson

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