The Siemens 3SF7844-8MS50-0MT0 is a Type 4 standard safety light curtain transceiver rated for 500 mm resolution and a 0 to 6.5 m protective range, with integrated muting and a PROFIsafe bus connection for the SIMATIC FS420i system. Type 4 per IEC 61496-1 means it can detect a 14 mm finger through the 500 mm resolution beam array — enough to stop a hazard before a hand reaches the danger zone.
The 500 mm resolution figure governs what the curtain can detect: a 500 mm object (roughly a torso) breaks the beam reliably. That's sized for access guarding where you don't need finger or hand detection — think palletizers, AGV corridors, or large-part assembly stations. The 0 to 6.5 m range gives you flexibility in bay depth; at the short end it still covers a single machine cell. Muting is integrated, so the curtain automatically suspends protection when a workpiece passes through on the conveyor, then re-arms — no external bypass logic required.
Integration notes
PROFIsafe connection means this transceiver talks safety over PROFIBUS/PROFINET to the SIMATIC FS420i safety controller — no hardwired safety relay needed for the safety loop. The muting lamp output is on the same bus, so the lamp status comes through the safety telegram. Mounting hardware and alignment brackets are standard for the FS420i family; the transceiver and receiver pair share the same form factor. No separate muting sensor module to wire in — the muting function lives inside the transceiver.