Chapter 1. Installation
12 DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Startup Guide (1- and 2-Channel)
1.7.6 Wiring a 0/4-20 mA Analog Inputs Option Card
To calculate energy measurement, the Model DF868 requires accurate temperature data from the measurement site.
Transmitters installed in the flowcell can provide this information via an optional 0/4-20 mA analog inputs card. This
option card includes two isolated 0/4-20 mA analog inputs (designated as A and B), each of which includes a 24 VDC
power supply for loop-powered transmitters. Either input may be used to process the temperature 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 have been 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 card or by
an external power supply. Figure 7 shows typical wiring diagrams, with and without an external power supply, for one
of the analog inputs.
Figure 7: Analog Input Wiring Diagram
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