Report by Exception (RBE)¶
Only publish tag values when they change, reducing MQTT bandwidth by 90%+.
Screenshot placeholder: RBE tag configuration
What is RBE?¶
Report by Exception means tags only publish to MQTT when their value changes, not on every poll cycle.
Benefits: - Reduce MQTT bandwidth - Lower SCADA processing load - Decrease network traffic - Ideal for slowly-changing values
How It Works¶
- Gateway polls tag normally
- Compares new value to last published value
- If changed → publish to MQTT
- If unchanged → skip publish
Configuration¶
Screenshot placeholder: Enable RBE on tag
- Edit tag
- Enable Is RBE
- Save tag
Tags with RBE enabled are automatically assigned to the RBE system tag group.
When to Use RBE¶
Good for: - Temperatures (slow changing) - Totalized values - Status values - Configuration settings
Not for: - Rapidly changing analog values - Critical alarms (use fast polling) - Values needed for trending
RBE vs Normal Publishing¶
| Scenario | Normal | RBE |
|---|---|---|
| Value changes every poll | 100% | 100% |
| Value changes once per hour | 100% | ~0.3% |
| Static value | 100% | 0% |
Best Practices¶
- Enable RBE for slow-changing tags
- Use normal publishing for fast data
- Consider SCADA's data needs
- Monitor for missed changes