The Siemens 3RK3321-1AA10 is a SIRIUS modular safety system expansion module providing 8 digital inputs in a 22.5 mm wide DIN-rail housing. It operates on a 24 VDC control supply and connects via screw-type terminals. The module is rated IP20 with finger-safe touch protection, suited for installation inside a control cabinet.
The 8 digital inputs expand a SIRIUS safety system's monitoring capacity — each input can evaluate a safety sensor (e-stop, guard switch, light curtain) in single- or dual-channel wiring. The 24 VDC supply is standard for safety controllers; the module draws its power from the backplane bus, so no separate power feed is needed. At 22.5 mm wide, it occupies one standard DIN-rail slot, matching the footprint of other SIRIUS modules. The IP20 rating means it is not sealed against moisture or dust ingress — it must live inside a panel with at least IP54 enclosure protection. Shock resistance of 15g / 11 ms and vibration resistance of 0.75 mm at 5...500 Hz (per IEC 60068-2-6) mean the module withstands typical industrial panel vibration from contactors and drives without loosening connections or intermittent faults. EMC immunity is specified: 2 kV burst on power ports (IEC 61000-4-4) and 4 kV contact / 8 kV air electrostatic discharge (IEC 61000-4-2). These levels are standard for industrial control cabinets and ensure the inputs do not false-trigger on nearby switching transients.
The module carries a substance prohibition date of 05/01/2012, indicating RoHS compliance (EU RoHS 2011/65/EU). It is designed for pollution degree 3 environments (industrial, with conductive or dry non-conductive pollution). Maximum installation altitude is 2000 m above sea level.