Glossary · Sensors and measurement
Position sensor
Also known as: Position transducer
German: Positionssensor
In automation, a position sensor is a sensor that detects or measures the position of an object, either as a discrete position (for example end position reached) or as a continuous linear or angular position value.
- Sensors
In one sentence
A position sensor detects or measures where an object is, as a discrete end position or as a continuous linear or angular value.
Example
Magnetic position sensors on a pneumatic cylinder report its retracted and extended end positions to the PLC.
How it applies
- Engineering: Discrete position sensors include limit switches, proximity sensors and cylinder switches; continuous sensors include encoders, resolvers, linear scales and magnetostrictive sensors. The choice depends on whether the controller needs an event or a value.
- Commissioning: Adjust switching points or zero offsets and verify them with the real mechanics.
- Safety: Position feedback used in safety functions, such as guard monitoring or safe speed and position, needs devices and architectures designed for that function.
- Documentation: Name each position sensor by function (for example clamp closed) as well as by tag, and describe the adjustment in the maintenance manual.
Position sensor vs. displacement sensor
A position sensor tells where something is. A Displacement sensor measures how far it moved. In practice, many sensors do both.