Overview
The Allen-Bradley MSR138DP is a Guardmaster monitoring safety relay that serves as the core component for implementing robust machine safety systems. This MSR138DP unit monitors dual-channel safety inputs from devices such as emergency stop buttons, safety switches, and light curtains, providing both immediate and time-delayed safety outputs for controlled machine shutdown sequences.
Key Features
- Dual-channel safety monitoring with cross-fault detection across inputs when configured in 2 N.C. mode
- Multiple output options: 2 N.O. safety instant and 3 N.O. safety delayed outputs
- Flexible input configurations: Can be connected in 3 different input wiring configurations: 1 normally closed, 2 normally closed, or 2 OSSD
- Reset flexibility: Accommodates either automatic/manual reset or monitored manual reset
- Compact DIN rail mount design with diagnostic LEDs for troubleshooting
- Safety certifications: Category 4 per EN 954-1; PLe per ISO 13849-1; SIL CL3 per EN IEC 62061
Technical Specifications
- Coil voltage options: 24V AC/DC or 115V AC (varies by model code)
- Output ratings: 6 A @ 24V DC or 3 A @ 115V AC (contact rating)
- Input configuration: Dual-channel (2 N.C.) with cross-fault detection capability
- Safety output quantity: 2 immediate + 3 delayed N.O. contacts
- Enclosure type: 45MM DIN rail mount, IP54 rated
- Reset options: Automatic/manual and monitored manual reset
- Mounting: Standard DIN rail
- Safety category: Category 4 / PLe / SIL CL3
Typical Applications
The MSR138DP is capable of monitoring various safety input devices such as emergency stop push buttons, safety switches, and light curtains. Its dual functionality provides both immediate and time-delayed safety outputs, allowing for applications that require a safe, controlled stop sequence, ensuring that hazardous motion has ceased before access is permitted.
Common uses include emergency stop circuit monitoring, safety gate interlocks, and light curtain supervision where time-delayed shutdown is required for controlled machinery deceleration.
Compatibility & Replacements
The MSR138DP is marketed under the Guardmaster and Minotaur product lines. The catalog number 440R-M23143 (24V AC/DC variant) and 440R-M23141 (115V AC variant) are direct references to this module. A closely related variant, the MSR138.1DP, offers different output configurations with two N.O. delayed and one N.C. delayed output in place of the three delayed outputs on the standard MSR138DP. Ensure proper coil voltage selection and output configuration match your specific control circuit requirements before ordering replacement units.
