ASIsafe extended safety monitor — 1 enabling circuit, 1 F-RO
The Siemens 3RK1105-1AG04-2CA0 is an ASIsafe extended safety monitor with one enabling circuit and one fail-safe relay output (F-RO). It is designed to guard hazardous zones on automated machinery, providing a monitored path for the enabling switch that an operator must hold to allow motion. The safe output relay is rated for DC-12 (DC-1) at 24 V at 3 A and AC-12 at 250 V at 3 A, so it can switch both DC and AC loads in the safety circuit. The unit's maximum response time is 40 ms, which sets the window for the safety function to react to an opening guard or released enabling switch. This monitor is rated for use up to Category 4 per EN 954-1, Performance Level e per EN ISO 13849-1, and SIL 3 per IEC 61508. Those ratings mean it is suitable for high-risk safety functions where a single fault cannot lead to loss of the safety function, and where redundant, monitored architecture is required. The 40 ms response time is the maximum interval from the input condition change to the output relay opening — critical for calculating the stopping distance of guarded equipment.
The 45 mm width fits a standard modular enclosure slot. Connections use spring-loaded terminals on removable plugs — strip length per the manufacturer's recommendation for spring-cage terminations. The monitor communicates over the AS-Interface protocol, integrating into an ASIsafe network where the safety-related inputs (E-stop, guard switches, enabling switches) are carried on the yellow AS-i cable alongside standard I/O. The spring-loaded terminals on the monitor handle the safe output wiring separately from the AS-i bus connection.