LJ12A3-4-Z/EX Inductive Proximity Sensor 2-Wire DC NO, 4mm Detection, 6–36V, IP66

The LJ12A3-4-Z/EX features a 2-wire DC normally open (NO) output. In its normal state (no target present), the circuit is open. When a ferrous metal target enters the 4mm sensing range, the internal solid-state switch closes, completing the circuit between the two wires. This configuration simplifies wiring by eliminating the need for a separate load power wire.

No, this is a standard inductive proximity sensor optimized for ferrous metals (iron and steel). Its sensing principle relies on the high magnetic permeability of ferrous materials. For reliable detection of non-ferrous metals, a capacitive or a specialized 'all-metal' inductive sensor would be required, as the reduced effect on the oscillator from non-ferrous targets falls outside this model's specified detection range.

This LJ12A3 model is shielded (flush-mountable). This means the sensing field is concentrated at the front face, allowing it to be installed flush with or embedded within a metal mounting bracket without a reduction in its nominal 4mm sensing distance. Non-shielded sensors require a clear non-metallic zone around the sides to function correctly. The shielded design offers greater installation flexibility in metallic machine structures.

Connect one wire (typically brown) to the positive DC supply voltage (within 6-36V). Connect the other wire (typically blue) directly to the PLC's digital input terminal. The PLC input's common must be connected to the DC supply negative (0V). The sensor acts as a switching load. Ensure the PLC input's impedance and current sink capability are compatible with the sensor's ≤300 mA rating.