APC UPS Pinouts

SUMMARY
=======
 
If you are having difficulty getting your American Power Conversion
(APC) uninterruptable power supply (UPS) system to work with Windows
NT, it may be due to the serial cable you are using. The following
information applies to APC Back-Ups models 250, 400, 450, 600, 900,
and 1250.
 
Make sure the following pins are connected:
 
   DB9 9-Pin Female Connector              DB9 9-Pin Male Connector
      (to PC serial port)                    (to UPS connector)
   ----------------------------------------------------------------
      Pin #5----------Ground------------------Pin #4
      Pin #8----------Power Failure-----------Pin #2
      Pin #4----------UPS Shutdown------------Pin #1
      Pin #1----------Low Battery---------Pin #5--[10k ohm]--Pin #8