Glossary · Automation fundamentals, platforms and components
Scaling
Also known as: Signal scaling, Normalization
German: Skalierung
In automation, scaling is the linear or nonlinear conversion of a raw signal value, such as ADC counts or a 4–20 mA current, into a value in engineering units, such as bar or °C, and the reverse conversion for outputs.
- Automation components
In one sentence
Scaling converts raw signal values such as ADC counts or 4–20 mA into engineering units like bar or °C, and back for outputs.
Example
A pressure transmitter with a 0–10 bar range delivers 4–20 mA; the PLC scales 12 mA to 5 bar.
How it applies
- Engineering: Scaling needs the raw range of the input module, the measuring range of the sensor and the target unit. Values outside the range (for example below 4 mA) should be treated as wire break or sensor fault, not as a valid measurement.
- Commissioning: Check scaling with at least two known points, for example the Zero point and the upper range value, ideally with a calibrator.
- Documentation: List range, unit and scaling for every analog signal in the I/O list and keep it consistent with sensor data sheets and HMI displays. When a sensor with a different range is installed, the scaling must be changed too, and the maintenance manual should say so.
Scaling vs. calibration
Calibration determines how far a sensor's output deviates from the true value. Scaling converts a signal into units, assuming the sensor is correct.