PLC – Scaling Analog values

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PLC - Normalizing, scaling analog values

Scaling is the process of converting, for example, a voltage or current signal coming from a sensor into a more usable form to match the corresponding unit such as bar, rpm, etc.

The scanned range of 0-10V voltage or 0-20 mA current for analog modules from Siemens (SM 334) values ​​are illustrated in the following. Also can be seen, that 10 V / 20 mA digitalized has the valor of 2764810.

PLC - Normalizing, scaling analog values

PLC - Normalizing, scaling analog values

These digitized values ​​can be more easily processed in the PLC when they are normalized / scaled. Normalizing (scaling) means converting the integer value (from the analog input 'PIW'), into a real number, which refers to the voltage on the analog input or analog output. For example, measuring a voltage of 0-10 V should correspond to the actual number from 0.0 to 10.0. The algorithm for this conversion is quite simple:

PLC - Scaling analog values

PLC - Scaling analog values

Work order:

Write a program that implements this algorithm.


  • 0:00 Introduction Analog Processing with PLC
  • 0:28 PLC and signals
  • 0:52 Analog-Digital-Converter ADC
  • 1:40 What is Scaling?
  • 2:31 Analoge Sensors