Euchner MGB-L1B-PNA-R-121857 Modular Guard Locking Safety System with PROFINET

The Euchner MGB-L1B-PNA-R-121857 is a modular guard locking safety system that integrates a PROFINET RT switch, emergency stop, and operator controls. Part of the MGB-PN series, this device provides a complete safety solution for machine guarding applications. It is an evaluation module with spring-force guard locking, designed to monitor the position of movable safety guards and lock them until safe conditions are met. The MGB system is built on a point-to-point network topology, enabled by the integrated real-time PROFINET switch, simplifying machine cabling. This all-in-one design integrates an evaluation module, bus module, and operator panel, reducing installation complexity and panel space requirements while increasing safety system reliability.

Guard Locking and Interlocking Functions

The MGB-L1B-PNA-R-121857 provides flexible use as either an interlock device or a guard locking device, configurable through the control system evaluation of the safe device data. Guard locking is spring force actuated, ensuring the guard remains locked even during power loss for fail-safe operation. Guard locking monitoring confirms the locked status before machine operation commences. The working principle utilizes a transponder-coded safety switch that reads a uniquely coded actuator, providing high-level protection against tampering and preventing defeat. The safe switch-off distance sar is specified at 20 mm for sliding door applications with deactivated guard lock monitoring, ensuring reliable detection of door position. For interlocking use, the safety outputs are enabled only when the actuator is within the defined sensing range.

Integrated Operator Controls and Emergency Stop

This MGB variant is equipped with three control elements: one emergency stop pushbutton compliant with ISO 13850, and two illuminated pushbuttons. The emergency stop is illuminated, providing high visibility in low-light conditions. The emergency stop contacts are 2 PD (positively driven) as required for safety circuits. The illuminated pushbuttons allow for custom labeling using the included adhesive labels, enabling application-specific control functions such as machine start, reset, or mode selection. The integrated control elements eliminate the need for separate operator panel components, consolidating safety and control functions into a single device.

PROFINET Integration and Communication

Equipped with an integrated PROFINET Real-Time (RT) switch, the MGB-L1B-PNA-R-121857 supports point-to-point network topology and simplifies system integration with PROFINET-based control systems. The device serves as a PROFINET IO device, communicating safe device status, guard locking position, and diagnostic data directly to the controller. Network connections are made via 7/8" power connectors (ANSI/B93.55M-1981) and M12 D-coded Ethernet connectors (IEC 61076-2-101), with the M12 interface used for PROFINET communication requiring Category 5e screened cables. The integrated switch reduces cabling effort by allowing multiple devices to be connected in a daisy chain configuration. PROFINET communication supports standard IO data exchange, making the device fully compatible with Siemens SIMATIC and other PROFINET masters.

Electrical and Operational Specifications

Power supply: 24V DC (reverse polarity protected, regulated, residual ripple<5%), with a current consumption of maximum 500mA. Rated insulation voltage Ui is 75V. Two separate DC supply lines (L1 and L2) are provided for device operation and for looping through power to downstream devices. The maximum feed-in current in the connection block (X1, X2) is 4000mA. An external fuse of at least 1A (slow blow) is required for the power supply X1. The system is designed for safety class III (PELV) installations. The device is rated for switching frequency of 0.25 Hz.

Mechanical and Environmental Ratings

Degree of contamination (external, per EN 60947-1): 3, requiring installation in a control cabinet or protected environment. Connection types: 7/8" power connectors for X1 and X2, M12 D-coded screened connectors for X3 and X4 (PROFINET). Rated impulse withstand voltage Uimp is 0.5 kV. EMC protection requirements comply with EN 61000-4 and EN 61326-3-1. The device is not intended for continuous high-frequency switching and operates reliably under standard industrial conditions. Storage temperature range is -25°C to 70°C.

Safety Integrity and Standards Compliance

The MGB-L1B-PNA-R-121857 meets requirements for performance level PL e and category 4 per EN ISO 13849-1, suitable for applications requiring the highest level of risk reduction. The transponder-coded actuator technology provides high coding level, protecting against manipulation. The device is certified for use in emergency stop circuits and safety gate monitoring applications under European machinery directive. Approvals include CE and cULus for international compliance.

Conclusion

The Euchner MGB-L1B-PNA-R-121857 safety guard system provides integrated PROFINET communication, spring-force guard locking, and operator controls including emergency stop and illuminated pushbuttons. With PL e / category 4 performance, it meets high safety integrity requirements for machine guarding in industrial automation applications.