The 3SF7844-8BB26-0SS1 is a Type 4 safety light curtain receiver from the Siemens SIMATIC FS420I series, paired with a matching transmitter to form an electro-sensitive protective device (ESPD). With 14 mm resolution and an 1800 mm protective height, it is rated for finger detection per IEC 61496-1/2 — meaning it catches a hand or finger reaching into a hazard zone before it contacts the moving part. The 0 to 6 m range covers most single-machine guarding layouts without needing a secondary curtain.
Integration and bus connection
This receiver communicates over PROFIsafe via the SIMATIC FS420I interface, so it drops directly into a Siemens safety CPU without a separate safety relay module. The bus connection handles both the safety signal and diagnostic data — blanking, muting status, and error codes — over the same cable. No discrete wiring to a safety PLC input is required; the PROFIsafe telegram carries the OSSD pair status.
14 mm resolution means the curtain detects a 14 mm diameter object anywhere in the field — that is finger-protection class, not just hand or body detection. The 1800 mm height covers a typical standing operator's reach zone; for taller openings you stack two curtains. Blanking is supported (noted in the description), so you can exclude fixed machine parts like a work table from the detection zone without disabling the entire curtain. The 0 to 6 m range is the operating distance between transmitter and receiver; at maximum range the light intensity drops, so keep the optics clean in dusty environments.