Siemens SIMATIC ET 200AL, System Manual

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Analog value processing
Function Manual, 06/2014, A5E03461439-AC
9
What you should know about analog technology
2
2.1 Overview
Introduction
This chapter is intended to familiarize you with the essential parameters of analog input
modules and analog output modules based on the fundamentals of analog technology. The
descriptions and examples provided on the following pages serve as a reference to the
manuals for the respective analog module and are intended to facilitate the handling of these
manuals.
Analog and binary signals
Binary signals can assume only 2 signal states: signal state 1 (voltage present) and signal
state 0 (no voltage present). In control engineering, it is frequently necessary to read,
process and output analog signals in addition to binary signals. In contrast to binary signals,
analog signals take on any number of values within a specific range. Possible analog
variables include:
● Temperature
● Pressure
● Speed
● Fill level
● pH value