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Sentinel™ User’s Manual 21
Chapter 1. Installation
1.8.7 Wiring 0/4-20 mA Analog Inputs
The two isolated 0/4-20 mA analog inputs (designated as C and D), each include a 24 VDC power supply for
loop-powered transmitters. Either input may be used to process a temperature signal, while the other input can be
used to process the pressure signal.
Note: To enter programming data during operation of the Sentinel, it will be necessary to know which input is
assigned to which process parameter. This information should be entered in Appendix B, Data Records .
The analog inputs, which have an impedance of 118 ohms, should be connected with standard twisted-pair wiring.
Power to the transmitters may be supplied either by the internal 24 VDC power supply on the analog input terminal or
by an external power supply. Figure 16 below shows typical wiring diagrams, with and without an external power
supply, for one of the analog inputs. Wire the analog inputs as shown on the label in the enclosure #1 rear cover (see
Figure 13 on page xxvii and Figure 20 on page xxxviii ).
Figure 16: Analog Input Wiring Diagram
+24V
IN +
IN RTN
IN +
+24V
IN RTN
+ -
+ IN
– OUT
+ IN
– OUT
24 VDC
POWER SUPPLY
With External Power Supply
With Internal Power Supply
Analog Input
Transmitter
Transmitter
Analog Input
Sensor
Sensor