The SICK WS/WE45-D250 is a coded safety interlock switch designed for the guard locking of movable safety guards, doors, and access points on machinery. It fulfills safety functions up to PL e according to ISO 13849-1 and SIL 3 according to IEC 62061. Its primary purpose is to reliably monitor the position of a guard (open/closed) and, crucially, to electromechanically lock the guard in the closed position until it is safe to open, preventing hazardous machine motion from being initiated while the guard is open or allowing access only after a safe state is achieved.