The Siemens 3RK3211-1AA10 is a SIRIUS modular safety system input module with 8 fail-safe digital inputs (F-DI), designed as a 4/8 F-DI configuration — four of the eight inputs can be used in 2-channel mode for redundant wiring to e-stops, light curtains, or guard door switches, while the remaining four handle single-channel signals like enabling switches or selector switches. Rated SIL 3 per IEC 61508 and IEC 62061, Category 4 per EN 954-1 and EN ISO 13849-1, and Performance Level e per ISO 13849-1 — this is the top safety integrity tier for a modular safety system, meaning it can be used in the highest-risk control loops where a single fault must not cause loss of the safety function and the probability of dangerous failure per hour is below 10⁻⁷.
Height is 102 mm; the screw terminals accept standard ferrule-terminated conductors, and the IP20 enclosure keeps live parts finger-safe once the cabinet door is closed.
Lifecycle and sourcing — active, not orphaned
What it evaluates — built-in logic for common safety functions
The module supports monitored start-up, EMERGENCY OFF function, protective door monitoring, enabling switch evaluation, selector switch evaluation, and two-hand operator panel evaluation — all handled internally without needing a separate logic module for these standard safety functions. It has no parameterizable outputs — this is a pure input module — and the 8 inputs are all safety-related; there are no non-safety or 2-channel-only inputs to confuse.
Environmental and EMC robustness
Rated for shock resistance of 15 g / 11 ms and vibration resistance of 0.75 mm across 5 to 500 Hz per IEC 60068-2-6, so it holds up on machines with moderate vibration — conveyor drives, press feeders, packaging lines. Surge voltage resistance rated at 500 V, and burst immunity at 2 kV on power ports per IEC 61000-4-4 — typical for industrial control panels without dedicated surge suppression on the safety circuit. Operates in 10 to 95 % relative humidity and pollution degree 3 environment — suitable for unconditioned plant-floor cabinets, not just climate-controlled rooms.