Safety light curtain receiver – Type 4, 14 mm, PROFIsafe
The Siemens 3SF7844-8MB04-0SS1 is a Type 4 safety light curtain receiver from the SIMATIC FS450i family, designed for finger-protection applications with 14 mm resolution and a 300 mm protected height. It covers a sensing range of 0 to 6 m and integrates muting capability, making it suitable for guarded zones where material must pass through without tripping the safety output. The PROFIsafe bus connection ties directly into a SIMATIC safety controller, eliminating the need for a separate safety relay or evaluation unit.
14 mm resolution means the curtain detects a finger-sized object (typically 14 mm diameter or larger) reaching into the hazard zone — this meets finger-protection class per IEC 61496-1, so it's the right choice for point-of-operation guarding where hand access must be prevented. The 300 mm protected height defines the vertical area covered; for a taller opening you'd stack multiple units or step up to a higher curtain. The 0–6 m range covers most machine cells, but if your application exceeds 6 m you'd need a different model. Muting allows the curtain to be temporarily bypassed (e.g., for a pallet passing through) while maintaining safety integrity — the muting sensors and logic are built into the FS450i architecture, not an add-on box.
Deployment context – guarding a real line
In a typical machine cell, this receiver pairs with the matching emitter (same resolution and height) and mounts on the hazard-zone perimeter. The PROFIsafe connection runs back to an F-CPU (e.g., SIMATIC S7-1500F or ET 200SP F), so the safety function is handled in the controller — no hardwired safety relay between the curtain and the main contactor. The muting function requires two muting sensors (usually photoelectric) positioned upstream and downstream; the FS450i logic handles the timing and validity checks. The 14 mm resolution means it catches fingers, so it's suited for press brakes, assembly stations, and robotic cells where an operator reaches into the work area.