Allen-Bradley Guardmaster MSR241P – Compact Safety Relay for E‑Stop and Gate Monitoring

The Guardmaster MSR241P is a compact, hardwired safety relay that typically handles dual‑channel emergency stops and guard door interlocks in machinery up to Category 4 / PL e applications. From my experience, it fits well when you need reliable safety contacts in a narrow, 22.5 mm DIN-rail footprint and you don’t want the complexity of a configurable controller. One thing I appreciate is how quickly it resets and how clearly the front LEDs guide troubleshooting during commissioning.

Company’s Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery time: In-stock items ship in about 1 week; no more than one month at the latest
• Payment: 50% advance payment; full payment prior to delivery
• Express delivery: FedEx, UPS, DHL

Key Features

• Dual-channel safety monitoring – Designed for E‑stop buttons and guard switches with cross‑fault detection for higher diagnostic coverage.
• Manual or automatic reset – Selectable reset behavior makes it easier to meet different machine safety concepts.
• EDM (External Device Monitoring) – Monitors downstream contactors so the relay won’t reset if the machine contactors are welded or stuck.
• Force-guided safety outputs – Redundant N.O. safety contacts, typically used to switch safety-rated contactors or power to drives.
• Auxiliary status contact – A monitoring (N.C.) contact for PLC indication or lamp annunciation.
• Compact 22.5 mm housing – Saves panel space on 35 mm DIN rail; wiring is straightforward and service-friendly.
• Clear LED diagnostics – You might notice that fault conditions and reset states are easy to interpret, cutting startup time in many cases.

Technical Specifications

A maintenance supervisor told us, “Swapping in the MSR241P cut our downtime—wiring is predictable, and EDM makes our safety contactor checks painless.” That seems to track with what we usually see on packaging lines and small assembly cells.

Related or Supporting Products

• Guardmaster MSR211P – Similar dual-channel relay widely used for E‑stop and gate circuits; slightly different I/O arrangements.
• Guardmaster MSR210P – Two‑hand control safety relay (Type IIIC) for presses or fixtures requiring synchronous actuation.
• Guardmaster GSR series (440R) – Newer safety relays like GSR DI or GSR EM provide modular options and broader diagnostics.
• 100S Safety Contactors – Pair with the MSR241P as the final switching elements, with mirror contacts for EDM.
• 440K / 440G Safety Interlocks – Tongue and guard‑locking switches commonly used as inputs to the relay.
• 440L Light Curtains – If you need presence sensing, these can be integrated with separate safety outputs to the relay or a GSR device.

Installation & Maintenance

• Cabinet & environment – Mount on 35 mm DIN rail in an enclosure meeting at least IP54 for dusty areas; allow ventilation space above/below the module.
• Wiring – Use dual‑channel wiring for E‑stops/guards, separate start/reset, and EDM to monitor downstream contactors. Use properly rated safety contactors on the output side.
• Power – Supply clean 24 VDC (regulated). In most cases, a dedicated safety power supply and proper grounding reduce nuisance trips.
• Functional checks – Verify stop time and reset behavior after wiring changes. Document the reset mode to align with your risk assessment.
• Routine maintenance – Inspect terminal tightness quarterly, test E‑stop/guard circuits, and confirm EDM operation. Keep vents clean to maintain temperature margins.
• Change control – If you replace downstream contactors or add loads, re‑validate the safety circuit category and diagnostic coverage.

Quality & Certifications

• CE, cULus, and TÜV compliant (typical for Guardmaster MSR family)
• Category 4, PL e (EN ISO 13849-1) and SIL 3 capability (IEC 62061), when applied per the manufacturer’s design guidelines
• RoHS compliant
• Manufacturer’s standard warranty applies; our supply warranty is 365 days as noted above