Glossary · Industrial communication
Proximity switch
Also known as: Proximity sensor, Non-contact switch
German: Näherungsschalter
In industrial automation, a proximity switch is a sensor that detects the presence of an object without physical contact and switches an output when the object enters its sensing range. Common types are inductive, capacitive, magnetic and ultrasonic; IEC 60947-5-2 covers proximity switches.
- Industrial communication
- Standards
In one sentence
A proximity switch detects objects without contact and switches an output within its sensing range (inductive, capacitive, magnetic).
Example
An inductive proximity switch detects when the steel cylinder rod reaches its end position and reports it to the PLC via IO-Link.
How it applies
- Engineering: The sensor type follows the target material and environment: inductive for metals, capacitive also for non-metals and liquids. Rated sensing distance, reduction factors for other metals and mounting (flush or non-flush) determine the reliable switching point.
- Communication: Proximity switches connect as simple digital inputs, via AS-Interface (AS-i) or via IO-Link, which adds parameters and diagnostics such as signal quality.
- Safety: A standard proximity switch is not a safety component. Monitoring guards or positions in a safety function requires devices designed for that purpose (for example coded safety sensors) as part of a validated Safety function.
- Documentation: The documentation team states the sensor type, sensing distance, output type (PNP/NPN, NO/NC), mounting conditions and adjustment instructions.
Proximity switch vs. limit switch
A limit switch is actuated mechanically by contact. A proximity switch works without contact, which avoids wear but makes the switching point depend on material, distance and environment.