The Siemens 3SF7844-8BB24-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420I family, rated for finger-protection class with a 14 mm resolution over a 1650 mm protective height and a sensing range of 0 to 6 meters. The 14 mm detection gap means it catches fingers reaching into the hazard zone, meeting the finger-protection class per IEC 61496-1. It communicates over a PROFIsafe bus connection, integrating directly into a safety-rated fieldbus architecture without a separate safety relay module.
Deployment context
This receiver is the sensing half of a Type 4 light curtain pair, deployed at the point of entry to a guarded hazard zone — typically a press, robot cell, or automated assembly station. The 1650 mm height covers a wide access area; the 0–6 m range suits mid-length spans common in perimeter guarding. PROFIsafe connectivity means the safety signal travels over the same PROFINET cable as standard I/O, reducing wiring and panel space compared to hardwired safety circuits.