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8.0 COMMUNICATIONS
8.1 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 communica-
tion, on battery and low battery signals. MultiLink, Liebert’s UPS monitoring and shutdown soft-
ware, is shipped with the UPS, along with a 10 ft. (3m) 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
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 dura-
tion of at least 2 seconds for the UPS to be shut down. The UPS communicates via serial communica-
tions using Liebert ESP II protocol.
8.2 Remote Shutdown Via the DB-9 Connector
The PowerSure PSI can be shut down remotely by shorting Pins 5 and 6 or via Pins 4 and 5 of the
DB-9 connector.
8.2.1 Any Mode Shutdown—Via Pins 5 & 6
When Pin 6 is shorted to Pin 5, the UPS output is shut Off regardless of what mode the UPS is oper-
ating in. The UPS cannot be started as long as the pins are shorted. When the short is removed, the
UPS output can be enabled by pressing the ON/Alarm Silence/Battery Test button.
8.2.2 Battery Mode Shutdown—Via Pins 4 & 5
While the UPS is operating on battery (with no battery test in progress), a 5-12VDC signal for 2 sec-
onds or longer is required to signal a shutdown. Signals for less than 2 seconds are ignored.
After Pin 4 receives the shutdown signal, a 2-minute shutdown timer inside the UPS begins a count-
down. The timer cannot be stopped. If utility power returns during the 2-minute timer countdown,
the shutdown timer continues until the end of 2 minutes and then the UPS turns Off. By default,
autorestart is enabled so the UPS will restart after 10 seconds. If autorestart is disabled via Multi-
Link software, the UPS remains Off until a manual restart.
Table 1 DB-9 pin assignment
DB-9 Pin Assignment Description
1 Low Battery (open collector)
2UPS TxD
3UPS RxD
4 Battery Mode Shutdown (5-12V)
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)
Pin Assignment Collector to Emitter*
54321
6789
(-)
(+)
330 Ohms
Open
Collecto
r
Open
Emitter