What it is and what it does
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.
Lifecycle and sourcing reality
For a BOM line requiring this exact order code, the part is sourced to order against an RFQ. Availability and current pricing are confirmed at quote time through independent distribution.
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.