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Serial port cable pinout

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  • Serial port cable pinout

    I spent last night trying to get DataLinkII V4.1.1 and Racepak Pro II to connect using serial port to enable Ana-B. This was the first time in 5 years we needed to use serial port.

    At first I took my universal USB-Serial adapter (Prolific PL-2303 XA chip), but DataLinkII gives "ERROR: Receiver timeout on serial port COM14"
    Next I let my Win 7 64 bit to upgrade the driver to latest version (Search automatically for updated driver software) and then after restart there was yellow rectangle in Device Manager next to port. I have used this adapter for years, but never tried to use it with Pro II serial port before. Now I'm stuck with this... uninstalling & removing the driver and installing the old driver back don't work either.

    Since there was a dead end with adapter I took another PC with physical COM-port next to dragster and soldered together a straight DB9 DTE-DCE (male-female) cable where RX, TX and GND where connected, but no handshaking. At this time I got "ERROR: Protocol error". Then I run out of battery and did not have time to put breakout box between connectors and debug more.

    We have never used the original serial cable which has been damaged at female end (at least it was our guess that it is original - or it is from MSD...). I tried to beep connectivity between pins to find out the handshaking thing before I soldered new cable, but it did not make any sense - so I binned it.

    Should the cable be straight 2-2, 3-3, 5-5 cable?
    What kind of handshaking is needed?
    Pins 1 & 9 won't be connected I guess since those are used for charging the Pro II.

    What are the following com port settings?
    - Bits per second
    - Data bits
    - Parity
    - Stop bits
    - Flow control

    Is there need to adjust FIFO buffer settings?

    I hope to get the answers soon so we can continue our test session.

  • #2
    Re: Serial port cable pinout

    The Pro II programming cable is a black 50' cable with the transmit and receive wires swapped, so a traditional extension cable, like the ones from MSD, probably won't work. We should see about getting a new programming cable to you.

    As far as the port settings go, the standard 9600, 8, 1 and NONE settings work fine. There's hardly ever a need to adjust these in Windows.

    If you are using version 3.4.1 or higher of Racepak's DataLink II software, the updated driver for the Prolific serial adapter should be present and should fix the driver conflict you are seeing in device manager. You can download the latest version of our software (version 4.1.1) from the 'Downloads' section of our website. If you still have problems with it, please don't hesitate to contact me.

    Todd Paton
    [email protected]
    949-709-5555 ext. 1652


    • #3
      Re: Serial port cable pinout

      Hi Todd,
      Thanks for your reply.

      First I try to get this working using COM1 and afterwards I concentrate on USB adapter issue. I found those drivers already, but didn't try those. Is it normally a plug-and-play using general USB adapter or do we need the DB9 female-DB9 male cable too?

      The cable I binned was black... Could not open connectors to look at wires.

      So when you say "transmit and receive wires swapped" it leaves quite many choices left...
      Do we need any additional wires for flow control (handshaking) or is it XON-XOFF?

      If we need handshaking we use "loop back" we use "partial handshaking" we use "full handshaking"
      Since 1 = +12V and 9 = Gnd for charging do we need to mix those with handshaking?
      Attached Files


      • #4
        Re: Serial port cable pinout

        You will need to use both a USB-serial adapter and the programming cable in order to communicate with the Pro II.

        Please check your Inbox for the pinouts of the cable.

        Let me know if you need anything else.

        Todd Paton
        [email protected]
        949-709-5555 ext. 1652