The Siemens 3SF7844-8BD17-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420I family, designed for point-of-operation guarding where a 30 mm resolution catches fingers and hand-sized intrusions before they reach the hazard. The 1200 mm protected height covers a typical vertical access zone on a press brake or assembly station, and the 0 to 18 m range gives you room to mount the emitter-receiver pair across a wide cell without worrying about alignment margin. Blanking capability means you can let fixed machine elements (a workpiece support, a fixture) pass through the curtain without tripping the safety output — a feature that keeps production running on parts that would otherwise need a separate guard.
Profisafe bus integration
This host receiver connects directly to a Profisafe bus, so the safety signal travels over the same PROFINET cable as standard I/O — no separate safety relay or hardwired feedback loop needed. The safety PLC sees the curtain as a standard F-device on the bus, which simplifies diagnostics and lets you map the blanking zones and muting logic in software rather than with external bypass switches. If your panel already runs a Siemens F-CPU, this receiver drops into the safety program with the GSDML file and a few TIA Portal configuration clicks.