The Siemens 3RK1105-1AE04-0CA0 is an ASIsafe Basis safety monitor with one enabling circuit — a single-channel safety output relay that drops the load when the safety function is triggered. The enabling circuit is rated for AC-12 at 250 V, 3 A, and for DC-12 (DC-1) at 24 V, 3 A, so it handles the control voltage of downstream contactors or safety relays directly. The 24 V control supply draws 1 A, the 115 V supply draws 0.1 A, and the 230 V supply draws 0.05 A — pick the supply voltage that matches your panel and size the power budget accordingly. The 40 ms maximum response time means the safety function reacts within two mains cycles — fast enough for Category 4 per EN 954-1, PL e per EN ISO 13849-1, and SIL 3 per IEC 61508. That covers most guarding applications like light curtains, safety mats, and two-hand controls where you need the output to drop before a person reaches the hazard.
The monitor mounts on a 35 mm DIN rail (EN 50022) or with screws — the 45 mm width matches a standard modular-width slot, and the 108 mm height by 120 mm depth fits a standard enclosure depth. IP20 protection means it's for the dry, clean side of the panel door, not the washdown zone. AS-Interface protocol support means it talks directly on the AS-i bus — no separate safety bus coupler needed. The reference code F per EN 61346-2 identifies it as a protective device in the circuit diagram.