Liebert Universal Monitor - Manual (Page 31)

Wiring and Connections - Main Board
23
4.3.1 Setting the 12VDC/24VDC Analog Power Jumper
The analog power jumper sets the common voltage that is applied to all of the analog input connec-
tions. The jumper permits the user to modify the voltage supplied to the sensors, according to the
power requirements.
The factory default position is 24VDC; it may be changed to 12VDC.
To change the analog power jumper setting:
1. Find the black analog jumper on the circuit board, as shown at
right. The jumper is at the bottom of the board near the middle
(see 1.7 - Controller Board Overview).
2. Decide whether your configuration requires the jumper to be
24VDC or 12VDC.
3. Set the jumper as needed:
• Set the jumper to the 24VDC position by placing the black
jumper on the middle and right pins.
• Set the jumper to the 12VDC position by placing the black
jumper on the middle and left pins.
4.3.2 Connecting the Analog Ground
The Universal Monitor features an analog ground
connection for four-wire sensors that have an
external power source. Such a four-wire sensor
requires a reference to ground because they get
power from an external power source.
A two-wire transducer, which does not have an
external power source, does not need to be con-
nected to the analog ground.
The analog ground connector has two terminals,
each of which can accommodate two wires. This is
adequate to connect four sensors that require a
reference to ground because they get power from
an external power source.
Connect the analog ground to an external four-
wire sensor as shown in the illustration at right.
485
+ —
+ —
(TOP)
(BOTTOM)
COMMS
422 TB9: ANALO
GROUND
AG
+ + — —
+ — + —
3-4 BOTTOM
1-2 TOP
Analog power jumper
+
+
+
—
—
+
(TOP)
(BOTTOM)
TB10: COMMS
4/20mA
Output
24V Input
TB9: ANALOG
GROUND
3-4 BOTTOM
1-2 TOP
Analog
ground
Analog
input
Four-wire
transducer
Sensor
with
external
power
24V from
external
power
source