Safety monitor for AS-Interface safety at the machine
The Siemens 3RK1105-1AE04-1CA0 is an ASIsafe safety monitor with one enabling circuit and one safe output relay (F-RO), designed to evaluate safety signals from AS-Interface slaves and switch the enabling path for a guarded machine zone. Rated for use up to Category 4 per EN 954-1, PL e per EN ISO 13849-1, and SIL 3 per IEC 61508, this monitor suits safety circuits where a single fault must not lead to loss of the safety function — typical for press guarding, robot cell access, or conveyor interlock zones. The 50 ms maximum response time means the enabling circuit drops within that window after a safety demand, which meets the speed requirements for most Category 4 / PL e applications without forcing a slower machine cycle.
Inputs and outputs connect via screw terminals with removable terminal blocks, so the base unit stays on the rail while wiring is swapped or pre-terminated off-panel. AS-Interface protocol support is built in, so the monitor communicates directly on the AS-i bus without an extra gateway module.
Contact ratings and switching capacity
The safe output relay is rated for 3 A at 24 V DC in DC-12 (DC-1) duty, and 3 A at 250 V AC in AC-12 duty — resistive load curves that cover typical solenoid valve and contactor coil switching within the enabling circuit. Control supply draw is 1 A at 24 V, 0.1 A at 115 V, and 0.05 A at 230 V — the 24 V figure is the one to budget for in a typical 24 VDC control panel.