Allen-Bradley MSR127TP Guardmaster Safety Relay

Allen-Bradley MSR127TP Guardmaster Safety Relay

The Allen-Bradley 440R-N23114, also identified as the MSR127TP Guardmaster safety relay, monitors dual-channel safety inputs and controls safety outputs.

Hardware Specifications

Industrial Safety Relay Input and Output Architecture

The MSR127TP accepts single-channel or dual-channel safety input configurations according to the connected field device.

Supported input arrangements include dual normally open contacts, dual normally closed contacts, and compatible light curtain PNP outputs.

The relay provides three normally open safety outputs and one normally closed auxiliary output for connected control circuits.

Reset selection supports Automatic/Manual operation or Monitored Manual reset through terminal cross-wiring.

Status LEDs identify power availability and the states of input channels IN 1 and IN 2 during operation.

The removable screw-terminal arrangement permits field wiring termination while maintaining the compact DIN rail housing format.

Frequently Asked Questions

Q: Can the MSR127TP operate with a single-channel safety input?

A: Yes. The supplied specifications identify single-channel and dual-channel input configurations, including NC contact arrangements.

Q: What output contacts are provided by the MSR127TP?

A: The relay provides three normally open safety outputs and one normally closed auxiliary output.

Q: What should be considered when installing the relay on a DIN rail?

A: Maintain secure DIN rail engagement, provide wiring clearance, and separate safety circuits from high-current conductors to reduce electrical interference.

Field Installation Guidelines

• Mount the relay securely on the specified DIN rail and verify mechanical engagement before wiring.
• Confirm the 24 VAC/DC supply polarity and terminal assignments against the applicable wiring documentation.
• Route safety input wiring separately from high-current switching conductors and motor power cables.
• Avoid parallel routing with high-noise conductors where electromagnetic coupling could affect input signals.
• Connect cable shields according to the machine grounding design and applicable electrical installation standards.
• Use the specified removable screw terminals and verify conductor retention after tightening.
• Select Automatic/Manual or Monitored Manual reset only after confirming the required machine safety circuit behavior.
• Verify each safety input independently before connecting the safety outputs to the final control circuit.
• Confirm PWR, IN 1, and IN 2 LED states during commissioning and fault investigation.
• Verify the enclosure and terminal protection requirements before installation in contaminated or exposed environments.