Chapter 1. Installation
14 DigitalFlow™ XMT868i Startup Guide
1.7.5c Wiring a 0/4-20 mA Analog Inputs Option Card
This option card includes two or four isolated 0/4-20 mA analog inputs (designated as A, B, C and D), each of which
includes a 24 VDC power supply for loop-powered transmitters. Either input may be used to process the temperature
signal, while the other input is used to process the pressure signal.
Note: To enter programming data during operation of the meter, 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 integral 24 VDC power supply on the analog input option card
or by an external power supply. Figure 5 below shows typical wiring diagrams, with and without an external power
supply, for one of the analog inputs.
Figure 5: Analog Input Wiring Diagram
Wire the analog inputs as shown on the label in the rear cover (see Figure 3 on page 6 and Figure 11 on page 24).
Note: The analog inputs option card can be calibrated with the Model XMT868i’s built-in analog outputs. However,
be certain that the analog outputs have been calibrated first. See Chapter 1, Calibration, in the Service Manual
for the appropriate procedures.
+24V
INPUT +
INPUT +
+24V
+–
+ IN
– OUT
+ IN
– OUT
Sensor
Sensor
Transmitter
Transmitter
Analog Input
Analog Input
24 VDC
POWER SUPPLY
With External Power Supply
With Internal Power Supply
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