PowerSure PSA Guide Specification
350 – 1000VA SL-23271 8/03
8
2.2.6 Communications
The UPS has a DB-9 (9 pin female) connector on the rear to allow UPS status communications
with a computer system running MultiLink™ software. The DB-9 is capable of supplying serial
communication, on battery and low battery signals. MultiLink, Liebert’s UPS monitoring and
shutdown software, is shipped with the UPS, along with a 10-ft. (3m) DB-9 cable required for
running MultiLink.
The UPS can signal “on battery” and “low battery” using opto-couplers. When the UPS is
operating in Battery mode, it can receive a signal from the host computer system that will shut
down the UPS (after gracefully shutting down the operating system on the host computer system)
when the remaining battery run time is low. The timing of the signal depends on MultiLink’s
configuration settings. This shutdown signal (5-12VDC) must have a duration of at least 1.5
seconds for the UPS to be shut down. The UPS communicates via serial communications using
Liebert ESP II protocol.
The PowerSure PSA has a USB interface port for communication that will work with the built-in
Microsoft Power Manager software on the user’s PC, if the PC is so equipped. It will provide UPS
status and manages the automatic orderly shutdown of the computer. The UPS (USB)
communications meets HID standard, version 1.11. All USB models are compatible with
Microsoft Windows 2000, Windows XP and Mac OS 10.2 or later. All USB models ship with a 6-
ft. (1.8m) USB cable.
The pin out configuration of the DB9 connector is:
Pin Assignment Description
1Low Battery (open collector)
2UPS TxD (typical RS-232 levels)
3UPS RxD (typical RS-232 levels)
4Battery Mode Shutdown (5-12V)
5Common
6Any Mode Shutdown (short to pin 5)
7Low Battery (open emitter)
8AC Fail (open emitter)
9AC Fail (open collector)
Maximum voltage and current on Pins 1, 7, 8, and 9 is 55VDC; 10.0 mA.