The EUCHNER MGB-PN is a modular safety door interlocking and guard locking system with an integrated control panel, designed to reduce the number of separate safety devices, control stations, and wiring connections around machine guard doors. It combines a safety interlock, guard locking mechanism, emergency stop, illuminated pushbuttons, and illuminated selector switches in a single unit mounted directly on the guard door frame. Communication to the safety PLC is handled by PROFIsafe over PROFINET, which carries both the safety‑critical interlock and E‑Stop signals and the non‑safety pushbutton and selector switch states through a single push‑pull RJ45 cable. The integrated PROFINET RT switch allows daisy‑chaining multiple MGB units or other PROFINET devices on the same network segment without additional switches. The system is pre‑assembled on mounting plates and includes all plug connectors, stack light connection, and adhesive labeling, reducing on‑site wiring to a single push‑pull connector and the 24 V DC supply.

Safety Architecture — PL e / SIL 3 Without Separate Safety Relays

• PROFIsafe over PROFINET: The safety‑critical signals from the guard locking mechanism, emergency stop button, and interlock status are transmitted as PROFIsafe telegrams over the same PROFINET cable that carries the standard I/O data from the pushbuttons and selectors. This eliminates the need for a separate safety relay module, dedicated safety wiring, or a second communication cable between the guard door and the control cabinet. The PROFIsafe profile is certified to SIL 3 (IEC 61508 / IEC 62061) and PL e (EN ISO 13849‑1).
• Guard Locking with 2000 N Retention Force: The guard locking solenoid engages automatically when the guard door reaches the closed position. With a locking force of 2000 N, the door remains securely closed during machine operation, preventing access to hazardous areas. The locking state is continuously monitored and reported via PROFIsafe. If the locking mechanism fails to engage—for example, if the door is not fully closed—the system prevents the machine from starting.
• Emergency Stop with Forced‑Opening Contacts (ISO 13850): The integrated emergency stop button complies with ISO 13850 and features forced‑opening contacts. Pressing the E‑Stop immediately triggers a PROFIsafe telegram that instructs the safety PLC to execute a controlled stop of the hazardous motion. The E‑Stop signal is processed at the highest priority within the PROFIsafe frame, independent of the pushbutton or selector switch states.

13 Control Elements — One Door, One Control Station

• 6 Illuminated Pushbuttons (1NO): Used for standard operator commands—machine start, machine stop, reset, acknowledge alarm, jog forward/backward, etc. Each pushbutton includes a white LED for status feedback (e.g., illuminated when the corresponding function is active or available). The 1NO contact type means each button provides one normally‑open signal to the PLC when pressed.
• 6 Illuminated 3‑Stage Selector Switches (2NO): Each selector switch has three positions and provides two normally‑open contacts. Typical applications include operating mode selection (Manual / Semi‑Automatic / Automatic), speed range selection (Low / Medium / High), or product type selection for recipe‑based production. The integrated LED illumination provides at‑a‑glance visual confirmation of the selected position.
• 1 Emergency Stop: Certified to ISO 13850, with forced‑opening contacts. The E‑Stop is wired directly into the MGB module and its state is transmitted as a PROFIsafe signal to the safety PLC. The E‑Stop meets the requirements for a Category 0 or Category 1 stop according to IEC 60204‑1.

Single‑Cable Connection and Simplified Wiring

• Push‑Pull PROFINET Connectors: Two push‑pull RJ45 ports (X3 and X4) provide the PROFINET connection. The push‑pull locking mechanism is more resistant to vibration than standard RJ45 clips and allows tool‑free insertion and removal. The integrated RT switch enables a point‑to‑point daisy‑chain topology: the PROFINET cable enters at X3 and exits at X4 to the next device, avoiding the need for external Ethernet switches in simple line topologies.
• 24 V DC Supply: The entire MGB-PN system—including the pushbutton LEDs, selector switch LEDs, and diagnostic LED indicators—is powered from a single 24 V DC supply (PELV, regulated, residual ripple < 5%). No separate supply for the illumination is required. A reverse‑polarity‑protected input prevents damage from accidental wiring reversal.
• Stack Light and Enabling Switch Ports: An M12 8‑pin connector (X6) provides a direct connection for an external stack light or signal tower, allowing installation of a visual status indicator on top of the guard door frame without additional wiring. The RC12 12‑pin port (X14) accepts an optional external enabling switch for maintenance or setup operations.
• Pre‑Assembled Kit: The MGB-PN ships with all connection plugs, adhesive labels for the pushbuttons and selectors, and the mounting plate already assembled. The installer mounts the plate on the door frame, connects the PROFINET push‑pull cable and 24 V DC supply, and the system is ready for PLC configuration.

Diagnostics and Status Indication at the Door

• 3‑Color LED for Operator Feedback: A single 3‑color LED (green, yellow, red) on the MGB module provides immediate visual indication of the system status. Green indicates normal operation with the guard door closed and locked. Yellow indicates the guard locking is active but the machine is in a safe state. Red indicates a fault condition—such as the guard door being open when it should be closed, or a PROFIsafe communication error.
• PROFIsafe Diagnostics in the PLC: Beyond the local LED, the safety PLC receives detailed diagnostic data through PROFIsafe telegrams: interlock state, guard locking state, emergency stop state, supply voltage status, and module temperature. These diagnostics can be displayed on the machine HMI, logged for maintenance records, or used for predictive maintenance.
• Mechanical Life of 2 × 10⁶ Cycles: The MGB module is rated for 2 million operating cycles under rated conditions. This long mechanical life reduces the need for preventive replacement and is consistent with the lifecycle expectations of industrial guard doors.

Applications

• Robot cell guard doors: Safety door with integrated start/stop and mode selection controls, reducing panel space and cabling around the cell perimeter
• CNC machine enclosures: Guard locking with E‑Stop, coolant on/off, and door status monitoring from a single device
• Automated assembly lines: Daisy‑chained MGB-PN units on a single PROFINET segment, each managing a different access point with local controls
• Packaging and food processing machinery: IP65 handle module for washdown environments with integrated safety and control functions
• Any safety application where combining guard locking, E‑Stop, and operator controls into one PROFINET‑connected device reduces wiring and simplifies the safety architecture