Overview
The 3RK3111-2AA10 is a Siemens 3RK31 central unit, part of the 3RK31 series of fail-safe control modules. It provides 4/8 fail-safe digital inputs, 1 fail-safe relay output (2 normally open contacts rated 24 V DC, 1.5 A), and 1 fail-safe digital output, all in a compact 45 mm wide housing rated IP20. Rated for 24 V DC supply and 4.5 W power consumption, it mounts on a DIN rail or with an optional screw lug. The unit is designed for safety-related applications up to SIL 3 / PL e, with a shock rating of 15g / 11 ms.
Function & operation
This central unit acts as the safety controller for a distributed fail-safe I/O station. The 4/8 fail-safe digital inputs (configurable as single-channel or dual-channel) monitor emergency stops, light curtains, and guard switches. The fail-safe relay output switches loads up to 1.5 A at 24 V DC, with two normally open contacts for redundant switching paths. Communication with a higher-level safety PLC or F-CPU occurs via PROFIBUS DP using an optional DP interface module, supporting 32-bit cyclical data exchange. The unit's 15g / 11 ms shock rating ensures it withstands vibration and impact on moving machinery or in transport applications.
Applications
The 3RK3111-2AA10 is used in safety-related automation systems for machine tools, packaging lines, presses, and robotic cells where fail-safe I/O must be distributed close to the hazard zone. Typical configurations include emergency stop circuits, two-hand control stations, and safety gate monitoring with dual-channel inputs.
Lifecycle & availability
The 3RK3111-2AA10 is an active, in-production product from Siemens. RoHS compliance is documented since 28-05-09. No end-of-life announcement or last-time-buy date has been issued. For BOM planning, the unit remains available through standard distribution channels; lead time is typically confirmed on RFQ.
Integration & mounting
Power consumption is 4.5 W. The unit is suitable for Class A EMC environments only; in residential settings it may cause radio interference, requiring mitigation. Pollution degree 3 rated, with a maximum operating altitude of 2000 m.
Compliance & environment
RoHS compliant since 28-05-09. The device is rated for Class A industrial EMC environments. Pollution degree 3 and a rated insulation voltage of 300 V.