Safety light grid receiver for access guarding
The Siemens 3SF7844-8MM51-0SS1 is a Type 4 safety light grid receiver in the SIMATIC FS420I family, designed for access and hazard-point guarding on automated lines. Its 900 mm protective height covers a typical conveyor infeed or robot cell entry, and the 6 to 70 m range handles longer spans like warehouse aisle gates. Type 4 per IEC 61496 means it detects a 14 mm finger-sized object and is rated for the highest safety integrity — SIL 3 / PL e — so it can serve as the primary guarding device without a second sensor.
PROFIsafe integration and muting
This receiver connects directly to a PROFIsafe bus via the SIMATIC FS420I interface, which means the safety signal travels on the same network cable as standard I/O — no separate safety relay needed. The built-in muting function (300 mm blanking) lets a pallet or workpiece pass through the light grid without tripping the safety circuit, so the line keeps running during material transfer. Muting is a standard feature here, not an add-on module.