The Siemens 3SF7844-8BD15-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420i family, with 30 mm resolution, 1050 mm protected height, and a sensing range of 0 to 18 m.
Type 4 per IEC 61496-1 means this curtain is rated for the highest safety integrity — it can detect a 30 mm object (finger-protection class) and is designed for use in safety circuits up to SIL 3 / PL e. The 1050 mm protected height covers a typical machine access zone; the 0–18 m range gives flexibility for longer guarding spans without needing a secondary curtain. Blanking capability (noted in the description) allows fixed obstructions like machine frames to be ignored, so the curtain can guard an irregular opening without nuisance trips.
Deployment context
As a Type 4 host receiver with PROFIsafe bus connection, this light curtain integrates directly into a SIMATIC safety controller environment — no separate safety relay needed between the curtain and the F-CPU. The 30 mm resolution makes it suitable for guarding robot cells, packaging machinery, and assembly stations where hand or finger access must be detected. In a washdown environment (e.g., food-and-beverage lines), verify the IP rating of the full curtain pair; the host receiver itself is typically IP65/IP67, but the mating emitter and cabling must match the zone's hygiene requirements.