The Siemens 3SF7844-8BD11-1SS1 is a Type 4 safety light curtain configured as the host receiver in a SIMATIC FS420I system. It provides a 30 mm resolution over a 750 mm protected height with a sensing range from 0 to 18 m, and integrates via PROFIsafe bus connection for direct communication with a safety-rated PLC. Type 4 per IEC 61496-1/2 means it is rated for the highest level of fault tolerance and detection reliability — suitable for guarding hazardous machinery where a failure could cause serious injury. The 30 mm resolution catches fingers approaching the hazard zone, while the 750 mm height covers a typical standing operator's reach zone. Blanking capability allows fixed or floating obscuration within the field, so the curtain can ignore a fixture or workpiece that passes through the beam pattern without disabling the safety function.
Deployment context
The receiver mounts to a machine frame or standoff using the standard FS420I bracket kit. PROFIsafe connection runs to a safety CPU (e.g., SIMATIC S7-1200F or S7-1500F) over a shielded M12 bus cable. The 0–18 m range covers most press, robot cell, and conveyor guarding layouts without a repeater.