Allen-Bradley MSR125H 440R-D23166 – Dual-Channel Safety Relay Module | GuardMaster MSR Series
Engineering Background
The Allen-Bradley MSR125H (Catalog No. 440R-D23166) is a dedicated safety relay module engineered by Rockwell Automation under the GuardMaster product family. Designed to meet the most stringent functional safety requirements in industrial automation, this module provides reliable dual-channel monitoring for emergency stop (E-stop) devices, safety gates, light curtains, and two-hand control systems. It is a cornerstone component in machine safety architectures across automotive, packaging, material handling, and process industries worldwide.
Product Positioning
The MSR125H targets procurement engineers and OEM machine builders who require a proven, standards-compliant safety relay with deterministic response times and broad input compatibility. As a Rockwell Automation GuardMaster module, it integrates seamlessly into Allen-Bradley control panels and supports both standalone and networked safety architectures.
Complete Technical Specifications
- Catalog Number: 440R-D23166
- Model: MSR125H
- Brand: Allen-Bradley / Rockwell Automation
- Series: GuardMaster MSR
- Safety Category: Category 4 / Performance Level e (PLe) per ISO 13849-1
- Safety Integrity Level: SIL 3 per IEC 62061
- Input Channels: Dual-channel (2-channel) monitored input
- Input Voltage: 24V DC / 115V AC / 230V AC (model-dependent)
- Output Contacts: 3 x Safety (N.O.) + 1 x Auxiliary (N.C.)
- Output Contact Rating: 6A / 250V AC (resistive load)
- Response Time: ≤ 20 ms (de-energize to safe state)
- Reset Mode: Manual monitored reset / Automatic reset (selectable)
- Operating Temperature: 0°C to +55°C
- Storage Temperature: -40°C to +85°C
- Protection Rating: IP40 (module body)
- Mounting: DIN rail (EN 60715 35mm)
- Housing Width: 22.5 mm
- Weight: Approx. 200 g
- Certifications: CE, UL, cUL, TÜV, ATEX (refer to datasheet for full listing)
- Standards Compliance: IEC 60947-5-1, EN ISO 13849-1, IEC 62061, EN 60204-1
- HS Code: 853649
Proven Application Environments
- Automotive Manufacturing: Robotic cell E-stop circuits, perimeter guarding, press safety interlocks
- Packaging Machinery: Safety gate monitoring on form-fill-seal lines, palletizers, and case erectors
- Material Handling: Conveyor emergency stop loops, AGV safety zones
- Machine Tool: CNC machining center door interlocks, spindle safety monitoring
- Process Industry: Hazardous area perimeter control, SIL 3 safety instrumented systems (SIS)
- Food & Beverage: Hygienic machine guarding with washdown-compatible enclosures
Engineering Advantages
- Dual-Channel Redundancy: Independent monitoring of both input channels detects single-point failures before they propagate to a hazardous state.
- Cross-Fault Detection: Internal diagnostics identify cross-wiring faults between input channels, preventing spurious safe-state bypasses.
- Selectable Reset Logic: Supports both manual monitored reset (requiring a deliberate operator action) and automatic reset for applications where re-energization is safe upon input restoration.
- Wide Input Voltage Range: Compatible with 24V DC control systems and legacy 115/230V AC panels without additional signal converters.
- Compact 22.5 mm DIN Rail Form Factor: Minimizes panel real estate while maintaining full Cat.4/PLe capability.
- LED Diagnostics: On-board status LEDs for power, input channel state, output state, and fault indication accelerate commissioning and troubleshooting.
- GuardMaster Ecosystem Compatibility: Pairs natively with Allen-Bradley safety sensors, light curtains (GuardShield), and safety PLCs (GuardLogix) for unified safety architecture.
System Architecture & Signal Flow
The MSR125H operates on a dual-channel monitored input principle. Both input channels (S11/S12 and S21/S22) must simultaneously present a valid closed-circuit signal for the safety output contacts (13/14, 23/24, 33/34) to energize. Upon detection of an open circuit on either channel — triggered by an E-stop actuation, safety gate opening, or wiring fault — the module de-energizes all safety outputs within ≤20 ms, driving the controlled machine to a safe state.
The monitored reset input (Y1/Y2) requires a deliberate rising-edge pulse from a separate reset pushbutton, preventing automatic restart after a safety event. The auxiliary output (41/42, N.C.) provides a feedback signal to the machine controller (PLC) for status monitoring and fault logging without compromising the safety circuit integrity.
Typical Wiring Topology: E-stop device → S11/S12 & S21/S22 inputs → MSR125H internal relay logic → Safety output contacts → Contactor coils / Drive enable inputs → Machine actuators.
Sourcing & Quality Verification
- Origin: Genuine Allen-Bradley / Rockwell Automation product, sourced through authorized industrial distribution channels.
- Traceability: Each unit carries Rockwell Automation catalog labeling with date code and serial number for full supply chain traceability.
- Inspection: Units are inspected for physical integrity, label authenticity, and packaging condition prior to dispatch.
- Warranty: Subject to Rockwell Automation standard warranty terms. Konmask.com provides 90-day return-to-base warranty on all stocked items.
- Counterfeit Risk Mitigation: Konmask.com does not source from grey-market or unverified secondary suppliers. All inventory is traceable to authorized distribution.
Procurement Process
- Confirm Part Number: Verify catalog number 440R-D23166 matches your BOM or replacement requirement. Cross-reference with Rockwell Automation Product Compatibility & Download Center (PCDC) if needed.
- Request Quote: Contact support@konmask.com with quantity, required delivery date, and destination country for a formal quotation including freight and duties estimate.
- Order Placement: Orders accepted via website checkout, purchase order (PO) by email, or bank transfer (T/T). Minimum order quantity: 1 unit.
- Lead Time: In-stock items ship within 1–3 business days. Out-of-stock items subject to sourcing lead time (typically 2–6 weeks).
- Export Compliance: This product may be subject to export control regulations. Buyer is responsible for compliance with applicable import/export laws in the destination country.
Technical FAQ
Q: Can the MSR125H monitor a single-channel E-stop device?
A: The MSR125H is designed for dual-channel input monitoring. Single-channel operation is possible in some configurations but will reduce the achievable safety category. Consult the product manual (Pub. 440R-UM013) for single-channel wiring options and the resulting safety performance level.
Q: Is the MSR125H compatible with Allen-Bradley GuardLogix safety PLCs?
A: Yes. The MSR125H safety output contacts can be wired directly to GuardLogix safety I/O modules. For integrated safety bus communication, consider the MSR57P or Compact GuardLogix with integrated safety I/O.
Q: What is the difference between 440R-D23166 and other MSR125 variants?
A: The 440R-D23166 catalog number specifies the exact input voltage range, output contact configuration, and approval markings. Always order by full catalog number to ensure correct specification. Refer to the Allen-Bradley GuardMaster MSR125 Selection Guide for variant comparison.
Q: Does this relay require an external fuse?
A: Yes. Rockwell Automation recommends external fusing on the safety output contacts per the installation instructions. Refer to the wiring diagram in the product manual for recommended fuse ratings.
Q: Can I get a certificate of conformity (CoC) or test report?
A: Konmask.com can provide available documentation upon request. Contact support@konmask.com with your order number after purchase.
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