SKU: NXB-GEN-621-019 | Version: 1.0 | Brand: NexBot Robotics
The NexBot Robotics 621-019 Door Interlock is a critical safety component designed to secure access gates and doors on automated robotic cells. This solenoid-controlled interlock switch prevents personnel from entering hazardous areas while the robotic system is in operation, ensuring compliance with rigorous machine safety standards. Its primary function is to lock a guard door shut and monitor its position, sending a signal to the safety controller only when the door is securely closed and locked. Key features include a high-performance safety rating of SIL 3 (IEC 62061) and PLe (ISO 13849-1), making it suitable for high-risk applications. The device provides a strong holding force of 2500 N, which reliably prevents the guard door from being opened accidentally or intentionally during a machine cycle. The housing is constructed from a rugged die-cast zinc alloy and is sealed to an IP67 rating, offering superior protection against dust and liquid ingress in demanding industrial environments. This ensures long-term reliability and performance even when exposed to coolants, particulates, and washdown procedures. Operating on a standard 24VDC supply, the 621-019 interlock integrates seamlessly with standard industrial safety control systems. Integrated LED indicators provide clear, at-a-glance status for locked, unlocked, and fault conditions, simplifying diagnostics and troubleshooting for maintenance personnel. The standardized mounting pattern allows for straightforward installation on common aluminum extrusion profiles and machine frames. This interlock is an essential element for building safe and compliant robotic systems used in applications such as automated welding, machine tending, high-speed packaging, and palletizing.
The NexBot Robotics 621-019 is a solenoid-controlled guard locking interlock switch. It is designed to prevent access to hazardous areas until the machine has reached a safe state, and is rated for use in safety functions up to SIL 3 and PLe.
When the guard door is closed, the actuator key enters the interlock. If the machine is running, a 24VDC signal energizes an internal solenoid, which moves a pin to trap the actuator, locking the door. Redundant internal safety switches monitor the door's position and locked status, sending signals to a safety controller via dual OSSD outputs.
The device features multi-color LEDs to provide clear visual status. A solid green light typically indicates the door is closed, locked, and the safety circuit is active. A yellow light indicates the door is closed but unlocked, while a red light signals a system fault or an open door condition.
During machine operation, the 621-019 interlock will be in a locked state with the guard door securely closed. The safety outputs will be ON, permitting the machine to run. The status LED will indicate the safe, locked condition.
To access the cell, an operator sends a request via the HMI or a pushbutton. The machine's safety controller executes a safe stop sequence. Once the hazard is eliminated, the controller de-energizes the interlock's solenoid, allowing the door to be opened.
When the solenoid is de-energized, the actuator key can be withdrawn by opening the door. In this state, the safety outputs are OFF, sending a stop signal to the machine's safety controller to prevent an unexpected startup.
If the interlock detects an internal fault, misalignment, or a wiring issue, it will enter a fault state. The safety outputs will switch to the OFF state, and the fault LED will illuminate. The machine cannot be started until the fault is cleared.
| Interval | Task | Notes |
|---|---|---|
| Daily | Visually inspect the interlock body and actuator for signs of physical damage, heavy contamination, or foreign objects. | To be performed by the operator before starting a shift. |
| Weekly | Perform a functional test by opening and closing the guard to ensure the machine responds correctly. | This verifies the integrity of the entire safety circuit. |
| Monthly | Check all mounting bolts on both the interlock body and the actuator key for proper tightness. | Machine vibration can cause fasteners to loosen over time. |
| Quarterly | Inspect the actuator entry point for debris and the actuator key itself for signs of wear or bending. Clean with a dry cloth. | Excessive wear indicates a potential alignment problem that must be corrected. |
| Annually | Verify the integrity of the wiring and connections. Check for chafed insulation or loose terminals inside the wiring compartment. | Perform this task during scheduled annual machine maintenance. |
| As Required | Re-validate the entire safety function after any changes are made to the guard, the interlock mounting, or the safety control logic. | Documentation of the re-validation is required by safety standards. |
| Symptom | Possible Cause | Solution |
|---|---|---|
| Guard door will not lock when commanded. | Poor alignment between actuator and interlock; No 24VDC signal to solenoid; Debris in actuator entry. | Check and adjust alignment. Verify with a multimeter that the lock signal is present at the terminals. Inspect and clear any obstructions. |
| Guard door will not unlock when commanded. | Binding of actuator due to force on the door; Solenoid coil has failed; Control signal is not being removed. | Ensure the door is not being pushed or pulled. Verify the unlock signal (0V) is present. If the solenoid does not release when de-energized, the unit may need replacement. |
| Safety outputs (OSSDs) are OFF when door is closed and locked. | Actuator is not fully seated; Internal switch failure; Mis-wiring to the safety controller. | Check door alignment to ensure full actuator insertion. Double-check wiring against the installation diagram. If the problem persists, replace the interlock unit. |
| Red FAULT LED is illuminated or flashing. | An internal self-check has failed; A cross-short is detected between the OSSD outputs. | Cycle power to the unit. If the fault persists, disconnect the output wiring to rule out an external short. Replace the unit if the internal fault cannot be cleared. |
| Nuisance tripping of the safety circuit. | Excessive machine vibration; Loose wiring connection at the terminal block; Actuator is on the edge of the sensing range. | Improve mounting rigidity or add dampening. Re-terminate all wires, ensuring they are secure. Adjust door alignment for better centering of the actuator. |
| Visible wear or damage on the actuator key. | Chronic misalignment causing the key to scrape the housing on entry/exit. | Immediately stop use. Re-align the guard door and interlock to ensure a straight, non-contact path for the actuator. Replace the worn actuator key. |
| Parameter | Value | Unit |
|---|---|---|
| Weight | 0.85 | kg |
| Material | Die-cast Zinc Alloy | |
| Voltage | 24VDC | |
| IP Rating | IP67 | |
| Country of Origin | US | |
| Dimensions | 155 x 52 x 50 mm |