Use the fields within the Alarm Limits section of the Analog Point tab to set limits for a point and specify whether an alarm or event is generated if the point exceeds those limits.
Some of the Alarm Limits fields are common to many analog points (see Configure the Limits for an Analog Point in the Geo SCADA Expert Guide to Core Point Configuration).
For information on Hysteresis, see Specify the Hysteresis - the Minimum Value Change that can Clear an Alarm in the Geo SCADA Expert Guide to Core Point Configuration.
For information on the Engineering Units Exceeded field, see Define how Over Range and Under Range Values are Processed in the Geo SCADA Expert Guide to Core Point Configuration.
- Persistence—Use this field to stop a change in value from affecting the point state until the point has been in that state for a specified time. This means the outstation will not process momentary changes of state and report such momentary changes to the server (see Use Persistence to Stop Fleeting Changes in Value from Changing a Point State).
Use the Persistence field to define any persistence time, in seconds. The persistence time begins whenever the point value drops below or rises above a state limit (by default, High-High, Low, and so on).
If, within the persistence time, the point value crosses a further limit in the same direction (that is, still continuing away from the Normal state, or still continuing toward the Normal state), the persistence period does not restart as it crosses the further limit. If the point value remains within the new state as the original persistence time elapses, the outstation updates the point state.
If the point value crosses back over a limit before the persistence time has elapsed, the point does not change state, and a new persistence time starts for the point value traveling in the new direction.
For examples of how persistence is used, see Use Persistence to Stop Fleeting Changes in Value from Changing a Point State.
If the Area of Interest feature is enabled on your system, an Area of Interest field is displayed within the Alarm Limits section. For information on this property, see Specify the Area of Interest Associated with a Point’s State-Related Alarms and Events in the Geo SCADA Expert Guide to Core Point Configuration.