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Computer with PS2 only to connect to RS232 DB9 device?

Discussion in 'General Electronics' started by Michal, Apr 9, 2004.

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  1. Michal

    Michal Guest


    I was wondering if someone knows how to do this. There are adapters from
    PS2>DB9 normally intended for mice, but I have a reverse situation:

    I need to connect a RS232 device (specialized digital modem) to a laptop
    only equipped with PS2 port.

    Normally the modem would use its proprietary software which uses COM1 on
    normally present DB9 on the PC and everything works.

    However in this case there is no DB9 on my laptop. QQ:

    1. Is there a way to buil some kind of adaptor to translate computer PS2
    port to RS232 DB9?

    2. If 1st is positive- can I then define the PS2 in this laptop to act
    as COM1 and communicate via this adapter with external RS232 device?

    Thanks for any clues, Regards M
  2. Garrett Mace

    Garrett Mace Guest

    I wouldn't bet my life on it being impossible to do, but that's what I'm
    thinking. There's a lot of rewriting that would be required in the operating
    system or BIOS, and I haven't even checked the difference in transmission
    speed. It would be a very involved project even if it was possible.

    The mouse adaptors are NOT RS232 to PS/2 adaptors. They reroute a few
    signals and possibly put a resistor across a pin or two, in order to signal
    to the mouse what kind of connector is being used. The mouse microcontroller
    then selects either serial or PS/2 operating mode based on that information.
    This is also commonly done with USB; that little adapter is NOT a generic
    USB to PS/2 adapter.

    Odds are very very good that your laptop has a PCMCIA or CardBus slot. Many
    serial port cards exist, you can buy one pretty cheaply new or used. Your
    application will work properly with such a card.
  3. If your laptop has no RS232 it almost certainly has USB. USB to RS232
    converters are quite common these days and not that expensive. They use to
    come with appropriate drivers so they can be considered normal COM-ports as
    far as your software concerns.

  4. Thomas Lutz

    Thomas Lutz Guest

    The PS2 port is not a RS232 serial port therefore you cannot use it as
    one. Probably the easiest thing to do would be to get a RS232 - USB
    add-on serial adapter. They are basically a small cable with a RS232
    DB9 on one side and a USB connector on the other. You plug the adapter
    into the USB port on your PC and then install a driver that comes with
    the adapter. When the adapter is connected to the USB port, windows
    behaves as if it has another COM port installed and any serial
    communication software can use the port just as if it were built into
    the motherboard.

    For more serial I/O tips tricks and free utilities, visit
  5. The PS2 port is not a serial port, even though you see that there is a
    mouse that can use it. The mouse is not realy serial. it is compatable
    to work this way from its internal firmware, and design.

    You can get a PCM type serial module that plugs in to one of the
    external PCM slots on your laptop. Most have this. This adabtor will
    give you the serial port you need. Or, you can get a USB to serial
    adabtor. The said devices will come with the proper software, and use
    drivers that are designed in to Windows to do what you want.

    This would be your best solution.

    Jerry G.
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