What this receiver does in the safety loop
The 3SF7844-8MD04-0SS1 is the receiver half of a Type 4 safety light curtain from the SIMATIC FS420I family, paired with a matching emitter to create a guarded zone. 30 mm resolution means it detects fingers and hands reaching past the plane — finger-protection class per IEC 61496-1. The 300 mm protected height covers a compact opening or conveyor infeed, and the 0 to 18 m range gives flexibility for longer spans in a single pair. Muting is built in, so the curtain can be temporarily overridden for material passage without stopping the machine — typical on palletizers or transfer stations where product breaks the beam during normal flow. PROFIsafe bus connection ties directly into a SIMATIC safety controller, eliminating hardwired OSSD pairs and reducing panel wiring.
Deployment context
Mounts in a standard safety light curtain column set or machine frame. PROFIsafe bus connection means the receiver communicates over a shielded M12 or RJ45 cable back to the safety CPU — no separate safety relay needed. The 30 mm resolution and muting function suit guarding zones where product must pass through without a stop signal, such as automated assembly cells or packaging lines.