When any object (typically a hand or body part) breaks a beam, the curtain's output switches state, signaling the machine's safety circuit to stop hazardous motion. This is the core of perimeter and access guarding per ISO 13849 and IEC 61496.
Deployment context
Safety light curtains of this class mount across machine access points — press brakes, robotic cells, assembly stations — where a person reaching into the hazard zone must trigger an immediate stop. The F3SJ series uses a slim housing profile suited for tight machine frames. The bulk packaging means the unit ships as a single piece, not a reel or multi-pack, which is typical for a one-off machine build or a spare on the shelf.