Allen-Bradley 440R-C23139 Guardmaster Safety Relay

Allen-Bradley Guardmaster 440R-C23139 MSR131RTP is a single-function monitoring safety relay used to convert safety-device inputs such as light curtains, safety mats, and emergency-stop switches into a fault-detecting output that can stop machinery. It is designed for 24 V AC/DC operation and delivers three normally open safety outputs (3NO) for interfacing with safety controllers and control relays, with catalog variants 440R-C23139 and 440R-C23139S representing MSR131RTP configurations. As part of the Guardmaster MSR131RTP family, this device monitors safety circuits in industrial automation to help meet safety requirements for machine guarding. Widely documented by Rockwell Automation, it is commonly used with Guardmaster safety sensors and controllers to implement reliable safety interlocks and stop conditions.