wenglorOPT123Reflex Photoelectric Sensor with Electronic Background Suppression — 550 mm Range, PNP Normally Open, IP65, M12 4-Pin, Roller Conveyor Design

Product Description

What this part is

A wenglor OPT123 reflex (diffuse) photoelectric sensor with electronic background suppression. It emits an infrared beam and detects the light scattered back by the object itself — there is no separate reflector and no separate receiver. What distinguishes it from an ordinary diffuse sensor is the background suppression, which is the whole reason the part exists.

Why background suppression is the specification that matters:
A plain diffuse sensor triggers on how much light comes back. That makes it hostage to the target: a matte black box at 200 mm and a polished steel plate at 500 mm can return the same signal, so the sensor cannot tell them apart. Anything reflective sitting behind the target — a machine frame, a guard, a wet floor, the far wall of an aisle — becomes a false trigger, and the fault is intermittent because it depends on what happens to be there.

Background suppression works on where the light comes back from, not how much. The sensor establishes a distance threshold; objects nearer than the threshold switch the output, objects beyond it are ignored regardless of how bright they are. In practice that means the sensor can be set to see a carton on a conveyor and stay blind to the steel frame 100 mm behind it, and it holds that behaviour whether the carton is white cardboard or black shrink-wrap.

The threshold is set on a scaled potentiometer on the sensor, so it is a screwdriver adjustment with a visible scale rather than a teach sequence.

What the sensor is actually designed for

wenglor states the design intent explicitly, and it explains the housing shape: these sensors were designed for use in accumulating roller conveyors. The compact body allows installation between the rollers, below the transport level, which puts the sensor out of reach of pallets, forklifts and anything that falls off the line. On an accumulation conveyor that is a real reliability advantage, because the usual failure mode of a side-mounted sensor is mechanical damage, not electronics.

Published specifications

Range: 550 mm.

Potentiometer at minimum: 220–270 mm. Potentiometer at centre: 320–400 mm. Potentiometer at maximum: 550–630 mm.

Switching hysteresis: 15 %.

Light source: infrared, 880 nm wavelength.

Service life at +25 °C: 100,000 h.

Risk group per EN 62471: 1.

Maximum ambient light: 10,000 lux.

Opening angle: 5°.

Supply voltage: 18–30 V DC.

Current consumption at 24 V: less than 30 mA.

Switching frequency: 100 Hz.

Response time: 5 ms.

Temperature drift: less than 10 %.

Operating temperature: −25 to +60 °C.

Switching outputs: 1.

Output type: PNP, normally open.

Switching current: 200 mA.

Output voltage drop: less than 1.5 V.

Short circuit, reverse polarity and overload protection: yes on all three.

Logic functions: none.

Protection class: III.

Setting method: potentiometer, scaled.

Housing material: plastic.

Full encapsulation: yes.

Degree of protection: IP65.

Connection: M12 x 1, 4-pin.

Weight: 96 g.

wenglor reference numbers: connection diagram 712, control panel OP1, mounting technology 420.

Output polarity

The output polarity of this sensor is fixed in hardware: PNP normally open, sourcing +V to the load when the target is present. It drives a sinking (current-sinking) PLC input card directly. It is a hardware characteristic of the sensor, so input card polarity decides compatibility.

The 200 mA switching current is generous for a sensor of this size — enough to drive a small relay or a pilot lamp directly, not just a logic input. Short-circuit, reverse-polarity and overload protection are all present.

Range and hysteresis data

The potentiometer figures are ranges rather than points: at minimum the threshold lands between 220 and 270 mm, at maximum between 550 and 630 mm. That spread is unit-to-unit variation.

The 15 % switching hysteresis is the gap between switch-on and switch-off distance. It prevents output chatter when a target sits on the threshold, and it means the object moves roughly 15 % of the set distance back out before the sensor releases.

The 5° opening angle is narrow, which is what makes the background suppression sharp, and it makes the sensor sensitive to angular alignment at longer distances.

Quantity and configuration

Sensor only, sold individually. No reflector is required — this is a diffuse background-suppression sensor. The mating cordset is an M12 4-pin type per wenglor connection diagram 712, and the bracket is wenglor mounting technology 420; both are separate wenglor part numbers.

Interchange guidance

Search forms include OPT123, OPT-123, OPT 123 and wenglor OPT123. Related wenglor families: the wider OPT reflex sensor range and the reflex sensors with background suppression for roller conveyor systems. The OPT123 is a fixed configuration; NPN output, other ranges and M8 connectors are separate part numbers in wenglor’s roller-conveyor sensor family. wenglor sensoric GmbH is a current manufacturer and this sensor is a current catalogue product, so a datasheet and pin diagram remain available directly from them.