The Siemens 3SF7844-8BB22-1SS1 is a Type 4 host receiver from the SIMATIC FS420I safety light curtain family. It provides 14 mm finger-protection resolution over a 1500 mm protective height, with blanking capability and a sensing range of 0 to 6 meters. The PROFIsafe bus connection integrates directly into a SIL 3 / PL e safety circuit without a separate interface module — the bus handles the safety protocol natively.
14 mm resolution means the curtain detects fingers reaching into the hazard zone — that is finger-protection class per IEC 61496-1. The 1500 mm protective height covers a typical machine access opening; the 0 to 6 m range suits most guarding distances on a production line. Blanking allows fixed or floating objects (e.g., a workpiece carrier) to pass through the field without tripping, while the rest of the curtain remains active. Type 4 per IEC 61496-2 means the curtain is self-checking and fault-tolerant — a single failure cannot cause loss of the safety function. This is the highest integrity level for electro-sensitive protective equipment, required for applications up to SIL 3 / PL e.