The Siemens 3RK1205-0BE00-0AA2 is a Safe SlimLine module S22.5F carrying 2 fail-safe digital inputs for mechanical switching contacts — think emergency-stop pushbuttons, safety limit switches, or door interlock contacts wired back to an AS-Interface safety network. Power comes from the AS-Interface bus itself: the module accepts 26.5 to 31.5 V DC per the AS-Interface specification and draws up to 45 mA from the bus. The two safe inputs read contact-open as Low and contact-closed as High, with a minimum 5 mA sense current at the High signal — enough to wet mechanical contacts and keep oxide films from causing nuisance open-circuit faults. IP20 protection means it belongs inside a panel or junction box, not out on the wet floor.
The module is 91 mm deep, 90 mm tall, and 22.5 mm wide — a single-width SlimLine footprint. Screw terminals accept the sensor wiring and the AS-Interface bus connection. Addressing is done via the front addressing socket; the ID/ID2 code is set to B/F. Yellow LEDs show the I/O status per channel; a green/red LED reports AS-Interface diagnostics and bus health. Because it's a safety module, the two inputs are fail-safe digital inputs (F-DI). That means they're designed to detect short circuits and cross faults — the safety PLC or AS-I safety monitor sees a discrepancy and shuts down the guarded zone. The module itself doesn't provide the safety evaluation; it's the field interface that brings the mechanical contact status onto the AS-Interface safety bus.