SOLUTION: apcupsd to Minisys (ProtectLI) and APC Smart Serial Interface

  • These are the things to do to configure apcupsd to a legacy APC UPS using a 940-0024C Smart Serial Cable,

    to a MiniSys (ProtectLi) computer with a RJ45 COM port.

    1. Must install pFsense VGA, single COM port will be dedicated to UPS.

    2. Minisys BIOS = Disable COM redirection. In Addition I set mine for 2400,n,8,1 or whatever speed ur UPS is currently set.

    3. Install apcupsd pkg and configure with params below.

    4. Build and use cable as shown below.


    This Doc created 3/14/2018. pFsense 2.4.2. FreeBSD 11.1.

    Name your UPS


    Legacy APC serial port

    UPSCABLE 940-0024C

    Smart Signalling

    UPSTYPE apcsmart
    DEVICE /dev/cuau0

    Leave the rest of params at default or customize to suit your need.

    Now you must build and use this custom cable, pinout as follows:

    Short pins 1 - 8.

    #    RJ45    DB9-M

    +– 1


    +-- 8

    #      3 ----- 1

    #      6 ----- 2

    #      5 ----- 9

    Here's one:


    UPDATE: Even Simpler. Use an USB-Serial dongle like the popular Prolific PL2303 which FreeBSD 11 has built-in driver, coupled with 094-0024c will do it. Then u save the 1 com port for console use. Mine came up as port cuaU0 (uppercase U) when hooked up to the USB3. So config DEVICE /dev/cuaU0.

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