Sensor fit and output logic
The SICK VL18-3P3140 is a photoelectric retro-reflective sensor in the VL18 cylindrical family, using an M18 threaded barrel (18 mm diameter, 66 mm body length) with a built-in M18 4-pin connector. It detects objects at up to 3.5 m (3.7 m max) by sensing the return of its own light beam from a separate reflector — no target-side wiring needed. The PNP output is configured dark-on (dark switching), meaning the output transistor turns on when the light path is blocked. That logic suits applications where you want a signal when an object interrupts the beam — part-present, jam detection, or edge-of-web sensing.
Washdown-rated barrel
Rated IP67, the stainless steel or nickel-plated brass barrel (material not specified in the listing but standard for this series) withstands hose-down and wet environments — food processing lines, car washes, outdoor conveyor gantries. The M18 connector mates with standard 4-pin cordsets; no panel wiring through the barrel. Operating temperature spans -25 to 70 °C, covering most factory floor and outdoor enclosure conditions without derating.