The Siemens 3SF7844-8BB17-1SS1 is a Type 4 safety light curtain host receiver from the SIMATIC FS420I family. It provides a 14 mm detection resolution across a 1200 mm protected height, with a sensing range of 0 to 6 meters. The 14 mm resolution means it catches fingers reaching into the hazard zone (finger-protection class per IEC 61496-1), making it suitable for guarding access to presses, assembly stations, and robotic cells where hand entry is the primary risk. This is the host receiver unit in a PROFIsafe bus-connected pair. It communicates safety status directly over PROFIsafe to a safety-rated PLC or drive, eliminating the need for a separate safety relay module in many architectures. The blanking function allows fixed objects (e.g., a workpiece fixture) to be ignored within the light curtain field without compromising safety integrity.
Integration notes
The host receiver connects via PROFIsafe to the safety controller — no hardwired safety relay needed. The 14 mm resolution and 1200 mm height determine the mounting brackets and alignment procedure: the emitter and receiver columns must be parallel and aligned within the manufacturer's angular tolerance. Blanking zones are configured in the safety PLC's F-parameter set, not on the unit itself. The 0 to 6 m range covers most machine access openings; if the gap exceeds 6 m, a different variant is needed.