Balluff BOS 21M-NA-PR10-S4 Retroreflective Proximity Sensor

Balluff BOS 21M-NA-PR10-S4 is a compact retroreflective photoelectric sensor from Balluff’s 21M family. It detects reflected light from a retroreflective target over 0.1 to 8 meters using a red 650 nm emitter with a divergent beam, and it delivers PNP outputs (normally open and normally closed) via a 4‑pin M12 connector when wired in the -S4S mode. The unit operates from 10 to 30 V DC. Its 15 x 50 x 42.5 mm block housing is zinc die‑cast with a powder‑coat finish, and the sensing face is PMMA. Front‑facing indicators include a yellow LED for output‑function indication and a green LED for stability, with a small potentiometer for threshold adjustments. The sensor can be mounted using the two M4 mounting holes, a dedicated mounting bracket, or clamps compatible with the dovetail housing profile. The NA variant aligns with Balluff’s North American catalog specifications for BOS 21M retroreflective sensors, sharing the same optical, electrical, and mechanical characteristics as other BOS 21M PR10-S4 devices, and is suitable for use on conveyors and automation lines where reliable presence detection of reflective targets is required.