What this starter kit delivers
The Siemens 3RK3923-2AC00 is a SIRIUS Modular Safety System starter kit — the bundle that gets you a central unit MSS ASIsafe Basic, spring-loaded terminals, a license for Safety ES V1.0 Premium software, and a USB PC cable. It is rated SIL CL 3 per IEC 61508 and PL e per ISO 13849-1, which means it meets the highest standard safety-integrity level for guarding hazardous motion on a production line. The PFHD sits at 7e-9 1/h (high demand rate per EN 62061), so the probability of dangerous failure per hour is negligible — this is the kind of spec a Tier-1 automotive line or a packaging cell demands for its safety circuit. Power draw is 4.5 W, and the dark period of the common drivers is 1 ms at 24 V — that 1 ms is the time the safety outputs stay off after a fault clears, preventing a fast re-start that could trap a technician. The input delay at the digital inputs maxes at 150 ms; the ingress acquisition time (the time it takes to register a sensor signal change) is 60 ms. Both are typical for a configurable safety controller and give the integrator enough window to debounce mechanical safety switches without false trips.
Connection is via spring-loaded terminals — no screwdriver needed for the power and I/O wiring, which speeds up panel assembly and reduces torque-verification steps.