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6.0 COMMUNICATION
6.1 DB-9 Connector
The UPS has a DB-9 (9 pin female) connector on the rear to allow UPS status communications with a
computer running Liebert MultiLink software in contact closure mode. The connection provides On
Battery and Low Battery notification.
When power is interrupted and battery power is low, Liebert MultiLink software can signal the host
computer to gracefully shut down the operating system.
6.2 Remote Shutdown Via the DB-9 Connector
The Liebert PSI XR can be shut down remotely by shorting Pins 5 and 6 or via Pins 4 and 5 of the DB-
9 connector.
6.2.1 Any Mode Shutdown Via Pins 5 & 6
When Pin 6 is shorted to Pin 5, the UPS output is shut Off no matter what mode the UPS is operating
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/Manual Self-Diagnostic Test button.
6.2.2 Battery Mode Shutdown Via Pins 4 & 5
While the UPS is operating on battery, a 5-12VDC signal for 2 seconds 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 begins a countdown. The shut-
down timer cannot be stopped: If utility power returns during the 2-minute countdown, the shutdown
timer continues until the end of 2 minutes and the UPS turns Off. The UPS will restart 10 seconds
after utility power returns.
6.3 Network Surge Protection Connectors
Network (in and out) connectors on the rear of the UPS provide transient voltage surge suppression
(TVSS) for network devices.
Table 4 DB-9 pin assignment
DB-9 Pin Assignment Description
1 Low Battery (open collector)
2 UPS TxD (not used)
3 UPS RxD (not used)
4 Remote Shutdown (5-12V); on-battery operation
5 Common
6 Output Off, (short to Pin 5, non-latching); any mode operation
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