The Siemens 3SF7844-6SS51-0SS0 is a Type 4 safety light grid transmitter from the SIMATIC FS420I family, designed for access guarding and hazardous-area protection on automated lines. It provides a 500 mm resolution over a 500 mm protective field height, with a sensing range of 6 to 70 m. Communication is via ASISAFE or PROFIsafe; as a transmitter unit it carries no output — the paired receiver handles the safety evaluation.
Type 4 per IEC 61496 means the light grid achieves the highest level of fault tolerance and self-checking — it can be used in safety applications up to SIL 3 / PL e when paired with a suitable safety controller. The 500 mm resolution detects a hand-sized object (finger protection is 14 mm; this is hand/arm detection). The 6 to 70 m range covers long conveyor or gantry zones. As a transmitter-only unit, it requires the matching receiver (typically a 3SF78..-6SS5.. variant) to complete the pair; no safety output is present on this order code.