Rockwell Automation Allen-Bradley 1769-IF4, User Manual

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1 Publication 1769-UM002B-EN-P - July 2005
Chapter
1
Overview
This chapter explains how analog data is used, and describes the 1769-IF4 and
-IF8 analog input modules and the 1769-OF2, -OF8C, and -OF8V analog
output modules. Included is information about:
•
the use of analog I/O
•
the modules’ hardware and diagnostic features
•
an overview of the 1769 analog input system operation
•
an overview of the 1769 analog output system operation
How to Use Analog I/O
Analog refers to the representation of numerical quantities by the
measurement of continuous physical variables. Analog applications are present
in many forms. The following application shows a typical use of analog data.
In this application, the processor controls the amount of fluid in a holding
tank by adjusting the valve opening. The valve is initially open 100%. As the
fluid level in the tank approaches the preset point, the processor modifies the
output to close the valve 90%, 80%, and so on, continuously adjusting the
valve to maintain the fluid level.
Figure 1.1 Analog I/O Application Example
Controller
Analog I/O
Module
Valve
Level Sensor
Analog input wired
to tank
Analog output
wired to valve