Allen-Bradley 440R-S12R2 Guardmaster Single Input Safety Relay

The Allen-Bradley 440R-S12R2 Guardmaster single-input safety relay is a DIN-rail mounted safety device that monitors a single safety input, such as an emergency stop, safety gate, or other safety circuits, and opens the safety outputs to stop hazardous equipment when the input is actuated. It provides two normally open safety contacts and one normally closed auxiliary contact, enabling safe shutdown and status signaling within Category 4 / SIL 3 / PLe capable safety systems when connected to a 24 V DC supply. The unit is designed for industrial environments and is commonly used in manufacturing equipment, robotic work cells, packaging machines, and automated production lines to support compliance with machine safety standards. Reset can be automatic or manual, giving flexibility for different process requirements, and it is intended for DIN rail mounting for easy integration into existing control panels. Key specifications include Manufacturer Part Number 440R-S12R2, Safety Inputs: single input channel, Safety Outputs: 2 NO contacts, Auxiliary Output: 1 NC contact, and operating temperature from -5 to 55 °C (23 to 131 °F). Common replacements and related models include 440R-S13R2, 440R-D22R2, and 440R-S12R1.