Choose sensors by what you need to detect and where. Inductive proximity sensors detect metal at short range; capacitive sensors detect most materials, including liquids through containers; photoelectric sensors detect objects at longer range; ultrasonic and laser sensors measure distance. Then match sensing range, output type (PNP, NPN, IO-Link, analog), connector and IP rating to the machine and environment.
Sensors tell your machine what is happening. The right type avoids false triggers and missed parts.
Sensor types
| Type | Detects | Typical range |
|---|---|---|
| Inductive proximity | Metal | Millimetres |
| Capacitive proximity | Most materials, liquids | Millimetres to tens of mm |
| Photoelectric (diffuse, retro, through-beam) | Most objects | Centimetres to metres |
| Ultrasonic | Objects and levels, including clear | Centimetres to metres |
| Laser distance | Precise position and height | Varies |
| Machine vision | Features, codes, defects | Camera field of view |
Checks
- Sensing range with margin.
- Target material, color and finish: shiny, dark and clear targets need care.
- Output: PNP, NPN, analog or IO-Link to suit your PLC.
- Connector and cable: M8 or M12, cable length.
- Environment: IP rating, temperature, washdown, vibration.
- Mounting and alignment.
Safety is different
Safety light curtains and scanners are safety components with their own ratings, separate from standard sensors. See safety and planning and our ROI guide.
Browse sensors and vision.
Common questions
PNP or NPN?
It depends on your PLC inputs. PNP (sourcing) is common in Europe and North America; NPN (sinking) is common in parts of Asia. Match the input card.
What is IO-Link?
A point-to-point communication standard that lets sensors send diagnostics and settings to the controller over a standard cable.
What IP rating do I need?
IP67 suits most factory areas with dust and splashes; IP69K suits high-pressure washdown in food plants.
When do I need machine vision?
When you need to inspect, read codes, measure features or guide robots beyond simple presence detection.