The Siemens 3SF7844-8TB13-1SS1 is a Type 4 host receiver in the SIMATIC FS420I safety light curtain family, specified for finger-protection applications with 14 mm resolution across a 900 mm protective height and a 0 to 6 m operating range. It connects via PROFIsafe bus, making it a direct drop-in for Siemens F-CPU safety systems on PROFINET networks.
The 14 mm resolution means this curtain catches fingers reaching into the hazard zone — finger-protection class per IEC 61496-1/2 — so it suits press-brake, pick-and-place, or assembly stations where hand access is possible but arm-through is not. The 900 mm protective height covers a typical vertical guarding zone for seated workstations or small conveyor infeed sections. The 0 to 6 m range is the transmitter-to-receiver separation; at maximum range the optical alignment tolerance narrows, so keep the pair within 4 m for easier commissioning on a crowded line.
Deployment context
As a host receiver in a Type 4 system, this unit handles the safety logic evaluation and PROFIsafe communication internally — no separate safety relay or F-Switch needed for the bus connection. Mounts in the standard FS420I column profile; the M12 bus connector and the 24 VDC power loop share the same cable run, so plan for a 4-conductor shielded cable (two for power, two for PROFIsafe) per the SIMATIC FS420I manual. The IP65-rated housing handles washdown in food-and-bev or automotive body-shop environments.