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

The Allen-Bradley 440R-S12R2, also cataloged as the 440R-S12R2 Safety Relay, operates as a dedicated hardware component for safety circuit monitoring and output control within Guardmaster machine safety systems. The relay processes dual-channel safety inputs from mechanical contacts, OSSD devices, and safety mats, executing fail-safe output switching through monitored relay contacts.

Hardware Specifications

Safety Logic Architecture and Deterministic Switching

The 440R-S12R2 is designed for single safety-zone monitoring applications requiring deterministic safety response. The relay supports dual-channel input validation and can monitor emergency stop devices, guard switches, safety interlock circuits, OSSD safety outputs, and pressure-sensitive safety mats.

Integrated Single Wire Safety (SWS) functionality permits interconnection with compatible Guardmaster safety relays without requiring additional hardwired status circuits. The relay continuously monitors input status, reset conditions, and output feedback to maintain defined safety logic operation.

The two immediate safety outputs are intended for direct safety circuit control, while auxiliary outputs provide diagnostic and status information to control systems and operator interfaces.

Frequently Asked Questions

Q: What safety performance level does the 440R-S12R2 support?
A: The relay is rated for PLe, Category 4 according to ISO 13849-1 and SIL CL3 according to IEC 62061 and IEC 61508.

Q: Which input device types are supported?
A: The universal dual-channel input supports mechanical safety contacts, OSSD semiconductor outputs, and safety mat devices.

Q: Does the relay support monitored manual reset functions?
A: Yes. Automatic reset, manual reset, and monitored manual reset modes can be selected using the integrated rotary configuration switch.

Field Installation Guidelines

• Mount the relay on a properly grounded 35 mm DIN rail.

• Verify supply voltage remains within the specified 20.4 to 26.4 VDC operating range.

• Use separate wiring routes for safety circuits and non-safety control circuits.

• Verify correct dual-channel wiring when connecting emergency stop or guard switch devices.

• Confirm reset mode selection matches the machine risk assessment and safety design.

• Inspect removable terminals for secure wire retention before energizing the system.

• Verify LED indicators during commissioning to confirm correct input, output, and fault status.

• Perform functional safety testing after installation, maintenance, or wiring modifications.