Rockwell Automation 1790D-NOV2/TNOV2 CompactBlock LDX Analog Modules - Manual (Page 11)

1 Publication 1790-UM001A-EN-P - March 2002
Chapter
1
Overview
This chapter explains how analog data is used, and describes
CompactBlock LDX analog input and output modules. Included is
information about:
•
the use of analog I/O
•
the modules’ hardware and diagnostic features
•
an overview of the analog input system operation
•
an overview of the 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.
Controller
Analog I/O
Module
Valve
Level Sensor
Analog input wired
to tank
Analog output
wired to valve