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Inductive Proximity Sensor

Detects metallic targets without contact by sensing changes in an electromagnetic field.

PLC address%I0.1
SignalMetal detected
BenchLive + faults
Try it: use this signal in PLC logic Learn the sensor first
FIELD DEVICE / 24 VDC

01 / Recognize it

What this sensor looks like

Learn the housing, active face, mounting, and connector before you meet it on a machine.

Representative real-world Inductive Proximity Sensor hardware on an industrial workbench
Representative field appearance · form factors vary by manufacturer

Hardware recognition

Know what to look for

Use the silhouette, active face, and connection style to identify the device before checking its part number and datasheet.

Body and mounting
Most inductive proximity sensors use a threaded M8, M12, M18, or M30 metal barrel.
Active face
The flat plastic end is the active face and must not be damaged by the target.
Cable and terminals
A rear cable or M12 connector carries 24 VDC and the switching output.
Field rule: identify by appearance, then verify the exact wiring, range, approvals, and output type from the device label and datasheet.

02 / Understand the principle

Watch cause become a PLC signal

Follow the physical event through the sensing element and into the exact controller value.

Signal story / live loop

Inductive Proximity Sensor: cause to controller

Paused

Now showingPhysical event

Steel flag moves closer → Oscillator is damped → %I0.1 = 1

03 / Test and commission it

Commission it on the bench

Move the process, adjust the setpoint, invert the logic and inject faults. Watch the PLC value respond immediately.

Commissioning bench

Inductive Proximity Sensor

24 VDC%I0.1
ON
7 mm
8 mm

PLC channel

%I0.1

RAW 1

Engineering value

7 mm

Metal detected

Output logic
Inject a field fault

Channel healthy

Signal is inside the expected operating range

Terminals
Brown +24 VBlue 0 VBlack PNP OUT

Commissioning note: Check the rated sensing distance against the actual target metal and mounting geometry.

Field guide

An inductive proximity sensor detects metallic objects without physical contact. Inside the sensing face is an oscillator coil that generates a high-frequency electromagnetic field. When a conductive target enters this field, eddy currents are induced in the metal, which damps the oscillator. The sensor's electronics detect this change and switch the output.

Sensing range depends on the target material. Mild steel gives the full rated range; aluminium and stainless steel reduce effective range by 30-50% due to their lower magnetic permeability. The manufacturer's datasheet always specifies a correction factor.

Shielded (flush-mountable) sensors contain the electromagnetic field within the face, allowing flush installation in a metal bracket. Unshielded sensors project a wider field and offer longer range, but require a metal-free zone around the sensing face.

Output wiring follows the same NPN/PNP conventions as photoeyes. Most industrial sensors are 3-wire: positive supply, negative/common, and signal. The signal wire connects to the PLC input.

Inductive prox sensors are the workhorse of factory automation — rugged, tolerant of oil and coolant, and immune to ambient light. They are not suitable for non-metallic targets; for plastics or liquids, a capacitive proximity sensor is the right choice.

Use this when…

  • Confirming a metal part is seated in a fixture
  • Detecting cam or gear tooth position for shaft feedback
  • Counting metal objects on a conveyor

Where you will see it

Automotive stamping

Inductive proximity sensors confirm steel blanks are seated correctly before a press descends, preventing tooling damage.

Machine tool

Shielded prox sensors detect the home position of CNC axes, providing repeatable reference points for every cycle.

PLC wiring reference

Trace the complete electrical path instead of treating the PLC tag as magic. Confirm the device datasheet before wiring real hardware.

  1. 1Brown +24 V
  2. 2Blue 0 V
  3. 3Black PNP OUT

Commissioning checkpoint

Check the rated sensing distance against the actual target metal and mounting geometry.

PLC address
%I0.1
Expected signal
Metal detected

Field questions

Frequently asked questions

What signal does a Inductive Proximity Sensor send to a PLC?

Metal detected is read at %I0.1. The exact electrical connection is Brown +24 V, Blue 0 V, Black PNP OUT.

How do you commission a Inductive Proximity Sensor?

Check the rated sensing distance against the actual target metal and mounting geometry.

Next skill

Connect it to PLC logic

60-second PLC integration challenge

Take the field signal into ladder logic, run the process tests, and prove the machine responds safely to both normal and abnormal conditions.

Open PLC challenge

Free first success

Use the inductive proximity sensor signal in PLC logic

Apply the wiring and commissioning model in a scored browser exercise, then save your progress and continue through the recommended path.

No installNo credit cardImmediate pass/fail feedback
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Technical reference and worked-example guide

Inductive proximity sensor and PLC input guide: field reference

Direct answer

The learner can explain the electromagnetic detection boundary, select PNP or NPN interface logic and trace the signal into a reliable PLC tag.

Written for automation learners and technicians selecting and diagnosing non-contact metal detection on PLC inputs.

System map / 02

NODE 01observable

Definition

The metal target, material correction, sensing distance, flush mounting, supply, output type and PLC input circuit.

NODE 02observable

Signal path

Target entry through oscillator change and sensor output to common, input channel, tag and machine response.

NODE 03observable

Worked example

Repeatable detection and release at a recorded distance with correct input polarity.

NODE 04observable

Limits

Small or nonferrous targets, recessed mounting, nearby metal, temperature, cable faults, leakage and chatter.

NODE 05observable

Common mistake

A target, range, mounting, supply, output, common, input or mapping fault.

NODE 06observable

Verification

The chosen sensor verified against its manual, target material, mounting and real input module.

Answer surface / 07

What is an inductive proximity sensor?

It detects nearby metal without contact by observing how the target changes an electromagnetic field at the sensing face.

Can an inductive proximity sensor detect plastic?

Normally no. For non-metal targets compare capacitive, photoelectric or ultrasonic sensing based on material, distance and environment.

Continue the signal path / 08

Real inductive proximity sensor footage

See this exact skill in the working simulator.

Watch the real browser product respond to the task on this page, then try the same practical workflow yourself. No slides, concept mockups, install, or credit card.

Try this in the browser
Inductive Proximity Sensor — How Metal Detection Works