MERIDIAN
UNIVERSAL GAS DETECTOR
INSTALLATION
4-28
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Figure 4-15: Connection for 3-Wire Sinking
2. Connect ground wire to device’s grounding/earth screw on its housing.
3. Unscrew the setscrew and housing cover, then pull on the LCD PCB/CPU PCB set, removing it from the four (4)
standoffs, to gain access to the lower PCB stack.
4. Connect positive (+) and negative (-) leads from 10 to 30VDC power supply wires to TB1 on the terminal/
relay/MODBUS RS-485 PCB. Specifically, the positive (+) connects to Pin2 (+V) and negative (-) connects
to Pin1 (GND) on TB1.
NOTE: These are examples of typical configurations. Other combinations exist and vary based on
each configuration.
NOTE: To prevent grounding issues, ensure you have a good ground/earth wire attached to the
housing and back to the receiver’s ground.
NOTE: It is not necessary to remove the wire ribbon cable from the upper and lower PCB stacks.
VDC Power
Supply
+
-
Receiver
+
-
Common
Output
4-20 mA
10 to 30 VDC
Shield
Common
+
-
+
-
Receiver
Receiver
ALARM3
NO
C
NC
NO
C
NC
FAULT
LP1
LP2
11 + - + -
LP3
+ - B A
10-30VDC
GND
+V
SW1 Up= Isloated
SW1 Down= Non-Isolated
ISO
SW1
NON
J3
Power Supply PCB
1
3
5
- +
NORMAL
NORMAL
HART
- +
1
3
5
- +
1
3
5
Dashed Lines Represent
Multi-Head Connetions
