Delock Fork Light Barrier 5 mm Type R with 4 Open Cable Ends PNP Light/Dark Switchable 2 m

In automated assembly lines, a fork light barrier like the Delock 91871 sits at a critical checkpoint, its 5 mm slot straddling a conveyor edge to detect passing components. With its compact PBT housing and 2 m cable ending in four open leads, it integrates directly into PLC input terminals without proprietary connectors. The sensor emits an infrared beam at 880 nm across the slot; when an object interrupts the beam, the PNP output toggles. A yellow LED on the housing gives immediate visual confirmation of switching state, while a small selector allows you to choose between light-on (output active when beam is unblocked) and dark-on (active when blocked) modes. This flexibility makes it suitable for both presence detection and gap monitoring in packaging, textile, and electronics manufacturing.

Key specifications

• Slot width: 5 mm, slot depth: 15 mm
• Output: PNP, light-on/dark-on switchable
• Supply voltage: 10–30 V DC, max. current consumption 20 mA
• Switching frequency: 1 kHz, response time 0.5 ms
• Light source: infrared LED 880 nm
• Connection: 4 open cable ends, cable length 2 m
• Housing material: PBT, protection class IP50
• Operating temperature: -25 °C to +55 °C
• Short-circuit and reverse polarity protection
• Status indicator: yellow LED

Why choose it

The Delock 91871 offers a straightforward, no-fuss solution for precise object detection in tight spaces. Its fork design eliminates alignment issues common with separate emitter-receiver pairs, saving setup time. The switchable light/dark output adapts to different logic requirements without rewiring. With robust electrical protections and a wide voltage range, it tolerates industrial power fluctuations. The 2 m cable with open ends gives you freedom to terminate as needed, reducing cable clutter and custom harness costs.

Ideal use cases

• Detecting small parts on conveyor belts in packaging machinery
• Edge monitoring of paper, film, or textile webs
• Counting components in feeder bowls or assembly stations
• Position verification in automated test fixtures
• Gap detection in label or print applications

Good to know

Since this sensor has IP50 protection, it is intended for clean indoor environments; avoid dusty or wet locations. The open cable ends require proper wiring according to the color code: typically brown (+V), blue (0V), black (output), and white (light/dark selection). Always verify polarity before powering. The sensor's fast response makes it suitable for high-speed lines, but ensure the object is large enough to fully block the 5 mm slot for reliable detection.