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Thread: limit on com ports?

  1. #1
    Low Bitrate
    Join Date
    Sep 2000
    Saint Peter, Mn

    Angry limit on com ports?

    I know you can use com1-4 pretty easy. But what would you do if you had a com5 and a program only allow to select 1-4?

    I have 4 serial ports right now: Touch Screen, Auto-Off, Auto-Tap, GPS. I have the X10, gonna try and use it inline with the TS.

    Anyone have a site that explains the usage of com ports? I would like to get everything working.

  2. #2
    Constant Bitrate
    Join Date
    Jul 2000


    The only limit on com ports is the resources in your computer you will need and IRQ and i/o numbers. When you get your I/O to give you the other 2 serials ports check it out to see if it will let you setup the port to all of the IRQs and stuff some won't which could be a pain getting the 2 ports running.


    my $0.02 cents (value is based on the intelligence of the person reading this message)

  3. #3
    Maximum Bitrate gizmomkr's Avatar
    Join Date
    Dec 2000
    Smyrna, Ga, USA


    Dragyn -

    Where did you get / make your auto off box ?
    Techonlogy on Wheels

  4. #4
    Variable Bitrate
    Join Date
    Aug 1999
    Yorba Linda, CA


    Some software is hard-coded to only allow COM1-COM4 to be selected. If you need more serial ports, move whatever devices have software support for higher ports (i.e. COM5-COMxx) to the new ports, to make room for devices that only have COM1-COM4 support.

    Jason Johnson
    Yorba Linda, California

    MPC Phase IV - *** PENDING ***

  5. #5
    Join Date
    Nov 2000
    St. Louis, MO, USA


    I think theoretically the number of COM ports is limited to 255... though I could be wrong there (it's been a while!)

    To support more than 3 or 4 COM interfaces though, you're probably going to have to start looking at high-end serial options like cards from a good supplier whose products I've learned to trust (and sometimes hate) over the years. They have good stable drivers for most Windows variants... and Linux has them built into the kernel (though you'd need a custom kernel to support them).

    Hope this helps.

  6. #6
    Retired Admin Aaron Cake's Avatar
    Join Date
    Jan 2000
    London, Ontario, Canada


    Remember: You can use the DOS MODE command to redirect unused LPT port designations to COM ports, and vice versa. This will allow you two more COM ports, if the software allows.

    Aaron Cake
    London, Ontario, Canada

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