LJ18A3-8-Z/BY PNP Inductive Proximity Sensor | Pro Tronix

Product Description

The LJ18A3-8-Z/BY is a rugged, industrial-grade inductive proximity sensor designed for precise, non-contact detection of metallic objects. Ideal for counting, positioning, and speed sensing, this sensor uses electromagnetic induction to detect ferrous and non-ferrous metals at a distance of up to 8mm. Housed in a heavy-duty, nickel-plated brass M18 threaded cylinder, it features a PNP Normally Open (NO) output configuration. This makes it highly compatible with standard industrial PLCs, relay modules, and microcontrollers. It is highly resistant to dust, moisture, and vibrations, ensuring reliable operation in harsh automation and machinery environments.

Pinout / Layout Connections

The sensor features an integrated 3-wire shielded cable with industry-standard wire color coding:

• • Brown Wire (VCC): Positive supply voltage input ($+6\text{V to }+36\text{V}$ DC).

  • Blue Wire (GND): Common system ground reference ($0\text{V}$).

  • Black Wire (OUT): Active-High PNP output signal.

    • Metal Object Detected (Active): The black output wire connects to VCC, outputting a positive voltage close to your supply level ($+6\text{V to }+36\text{V}$ depending on supply input).

    • No Metal Detected (Idle): The output floats (Normally Open).

    • Microcontroller Note: Because this sensor operates at higher industrial voltages, use a simple voltage divider or an optocoupler if interfacing with a $5\text{V}$ Arduino or $3.3\text{V}$ ESP32 to safely step down the black signal wire voltage.

Applications

• High-Accuracy Metal Detection: Spotting gears, metal shafts, cans, or metal plates in mechanical linkages and packaging lines.

• Rotational Speed / RPM Sensing: Positioned next to a spinning metal target, like a sprocket or bolt head, to measure rotation speed.

• Industrial Limit Switching: Reliably monitoring physical travel limits on CNC machinery, automated gates, or material handling systems.

Compatibility

• Industrial PLCs: Seamlessly interfaces with $12\text{V}$ or $24\text{V}$ sourcing (PNP) PLC input cards.

• Microcontrollers (Arduino / ESP32): Requires a voltage divider or optocoupler level-shifter on the black wire, as the sensor’s output logic matches its supply voltage ($6\text{V} – 36\text{V}$).

• Sourcing Relays: Can directly trigger $12\text{V}$ or $24\text{V}$ relay coils connected between the Black output wire and Ground.

Technical Specifications

What’s in the Box

• 1 x LJ18A3-8-Z/BY Inductive Proximity Sensor (with integrated 1.2-meter cable).

• 2 x Metallic Mounting/Retaining Washers and Hex Nuts.

Available now from Pro Tronix with guaranteed quality and fast delivery nationwide.