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COMMUNICATIONS
DB-9 Connector
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 3m(10-
ft.) DB-9 cable required for running MultiLink.
When MultiLink is installed on the host computer, 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 com-
puter 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 2 seconds for the UPS to
be shut down. The UPS communicates via serial communications
using Liebert ESP II protocol.
* Maximum voltage and current on Pins 1, 7, 8, and 9 is 55VDC; 10.0 mA.
DB-9 Pin Assignment Description
1 Low Battery (open collector)
2 UPS TxD (typical RS-232 levels)
3 UPS RxD (typical RS-232 levels)
4 Battery Mode Shutdown (5-12VDC, 10-24 mA max)
5 Common
6 Any Mode Shutdown (short to Pin 5)
7 Low Battery (open emitter)
8 Utility Fail (open emitter)
9 Utility Fail (open collector)
DB-9 Pin Assignment Collector to Emitter*
54321
6789
(+)
Open
Collector
(-)
Open
Emitter