What this safety monitor does on the line
The Siemens 3RK1105-1BE04-4CA0 is an ASIsafe extended safety monitor with two enabling circuits, designed to supervise safety functions on an AS-Interface network. The 40 ms maximum response time means it reacts fast enough for most guarding applications — light curtains, e-stops, interlocked gates — without forcing a slower safety PLC scan. Rated for use up to Category 4 (EN 954-1), Performance Level e (EN ISO 13849-1), and SIL 3 (IEC 61508), it covers the highest integrity levels for risk reduction in industrial machinery. That makes it suitable for press brakes, packaging lines, or robotic cells where a fault could cause serious injury.
The two enabling circuits (safe relay outputs) are rated for 3 A at 250 V AC (AC-12 resistive load) and 3 A at 24 V DC (DC-12 / DC-1). That's enough to switch contactors, solenoid valves, or indicator lamps directly — no interposing relay needed for moderate loads. The 24 V DC supply input draws 1 A; the 115 V and 230 V control inputs draw 0.1 A and 0.05 A respectively, so the power budget on the AS-i bus or auxiliary supply is modest.
At 108 mm high and 120 mm deep, it fits standard control cabinets without crowding adjacent modules. IP20 protection means it belongs inside a sealed enclosure — not on the machine frame where washdown or dust could reach it. Connections are via removable screw terminals, so you can pre-wire the cabinet and plug the monitor in during commissioning. The inputs and outputs share the same terminal type, which simplifies the BOM for panel builders.