What is the difference between the protective field and the warning field on the NexBot 332-009 Laser Safety Scanner?
Learn the distinct functions of the protective field (safety stop) and the warning field (pre-warning) on the NXB-GEN-332-009 Laser Safety Scanner for proper area guarding.
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The NexBot Robotics 332-009 Laser Safety Scanner (SKU: NXB-GEN-332-009) is a key component for creating safe, dynamic industrial workspaces. A common point of inquiry involves understanding the two primary configurable zones it generates: the protective field and the warning field. While both monitor for intrusions, they serve different purposes and trigger different system responses. Properly configuring these fields is critical for achieving both safety compliance and operational efficiency.
Answer
The fundamental difference lies in their safety rating and the machine response they initiate. The protective field is a safety-rated function that triggers a machine stop, while the warning field is a non-safety function that typically triggers an alert or a speed reduction.
Protective Field (Safety Field)
The protective field is the primary safety zone. Its purpose is to stop hazardous machine motion before a person can reach the hazard point.
- Function: When the scanner detects a person or object inside this defined area, its safety outputs (OSSDs - Output Signal Switching Devices) immediately switch to an OFF-state. This signal is sent to the machine's safety control system (e.g., a safety PLC or safety relay), which then removes power from machine actuators, bringing the equipment to a safe stop.
- Safety Rating: The protective field function is designed and certified to meet high safety standards (e.g., SIL 2, PL d). Its operation is continuously monitored for faults.
- Range: The NXB-GEN-332-009 supports a protective field with a maximum radius of 5.5 meters.
- Configuration: The size and shape of this field must be calculated based on the overall stopping time of the hazardous equipment to ensure an intruder is detected and the machine stops before the hazard can be reached.
Warning Field (Alert Field)
The warning field is a non-safety-rated zone configured outside of the protective field. Its purpose is to provide an early warning before a safety stop is initiated.
- Function: When the scanner detects a person or object inside the warning field, it triggers a separate, non-safety output. This output is not tied to the machine's emergency stop circuit. Instead, it can be used to activate an audible alarm, flash a warning light, or signal a robot controller (like those for the NexBot R-50 or C-10 series) to reduce its operating speed.
- Safety Rating: This function is not safety-rated. It is an auxiliary feature and must not be used as the primary means of protection.
- Benefit: The warning field helps prevent unnecessary machine downtime. By alerting personnel that they are approaching a hazardous area, it allows them to correct their path without triggering a full system shutdown, thereby improving productivity.
Key Differences Summary
| Feature | Protective Field | Warning Field | | :--- | :--- | :--- | | Primary Purpose | Stop hazardous motion | Alert personnel, reduce machine speed | | Safety Rated | Yes (e.g., SIL 2, PL d) | No | | Output Type | Safety OSSD Outputs | Standard (Non-Safety) Output | | Machine Response | Immediate safe stop | Audible/visual alarm, speed reduction | | Configured Location| Innermost zone, closest to hazard | Outer zone, surrounding the protective field |
Configuration Tips and Best Practices
When setting up the NXB-GEN-332-009 scanner using the provided configuration software, consider the following:
- Risk Assessment First: Always begin with a thorough risk assessment of the application. This will determine the required size of the protective field based on system stopping performance and potential approach speeds.
- Field Contouring: Utilize the scanner's 275° scan angle to create precisely contoured fields that match the shape of the hazardous area. This avoids nuisance trips from objects outside the intended zone while ensuring complete coverage.
- Field Sets: For applications with changing conditions, such as AGVs or robotic cells with multiple operating modes, configure multiple field sets. You can switch between them dynamically to adapt the size and shape of the protective and warning zones to the current task.
- Verification: After configuration, always verify the performance of both fields. Use a test piece of a defined size and reflectivity to walk the boundary of each field, confirming that the correct outputs (OSSDs and warning output) are triggered at the correct locations. Document these tests as part of your commissioning process.
Related Topics
- Calculating Minimum Safety Distance for Safety Scanners
- Integrating the NXB-GEN-332-009 with a NexBot Robot Controller via EtherNet/IP
- Troubleshooting 'OSSD Fault' Alarms
- Best Practices for Mounting Safety Scanners to Avoid Interference