The Allen Bradley MSR211P (part number 440R-N23132) is a specialized safety monitoring relay within the GuardMaster family. Designed for high-reliability applications, it acts as a critical logic interface between safety input devices—such as E-stop buttons, safety gates, or light curtains—and the final switching elements of a machine’s power circuit.

 

Product Overview

The MSR211P is a modular safety relay that supports a variety of input configurations, including 1 N.C., 2 N.C., or light curtain (OSSD) signals. It is engineered to perform self-monitoring and redundancy checks, ensuring that a single component failure does not lead to a loss of the safety function. This model is particularly valued for its “Power-to-Release” and “Power-to-Lock” logic support, making it ideal for interlocking applications where controlled access is mandatory.

 

Technical Datasheet & Parameters

 

Country of Origin

The Allen Bradley MSR211P is designed and manufactured in Germany (or the USA, depending on specific production batches).

 

Application Fields

• Emergency Stop Circuits: Monitoring single or dual-channel E-stop palm buttons.
• Gate Interlocking: Ensuring machine power is disconnected when a safety fence door is opened.
• Light Curtain Integration: Interfacing with OSSD outputs from safety light screens.
• Robot Cells: Managing safety zones for human-robot collaboration areas.
• Packaging Lines: Providing localized safety control for conveyors and palletizers.

 

Technical Description

Technically, the MSR211P utilizes a redundant internal circuit with force-guided (positively driven) relays. It continuously monitors for short circuits across the input channels and performs a cross-fault check to ensure the integrity of the safety loop. The “P” suffix in the model name indicates the use of removable (pluggable) terminal blocks, which significantly reduces downtime during maintenance or replacement. The unit features a diagnostic LED array on the front panel that indicates the status of the power supply (PWR), input channels (CH1/CH2), and the output state (OUT).

Usage Instructions

1. DIN Rail Mounting: Snap the 22.5mm housing onto a standard 35mm DIN rail inside a protected control cabinet (IP54 minimum recommended).
2. Input Wiring: For a Category 4 system, connect dual-channel N.C. contacts from your safety device to terminals S11-S12 and S21-S22.
3. Reset Configuration: Bridge terminals S33-S34 for automatic reset, or install a normally open momentary push-button across these terminals for “Monitored Manual Reset.”
4. Output Connection: Wire the 2 N.O. safety outputs (13-14 and 23-24) in series with the coils of the machine’s primary contactors.
5. External Device Monitoring (EDM): Loop the N.C. auxiliary contacts of your main contactors through the reset circuit (S34) to ensure the contactors have physically opened before a reset is allowed.

For technical drawings and current availability of the MSR211P 440R-N23132, please visit our safety components resource center.