Use the fields within the Alarm Limits section of the TBox Analog Point tab to set limits for a point and specify whether an alarm or event is generated if the point exceeds those limits.
Many of the Alarm Limits fields are common to many analog points (see Configure the Limits for an Analog Point in the ClearSCADA Guide to Core Point Configuration).
- Hysteresis: Use this to define the amount by which an analog point’s value has to decrease below a high limit, or increase above a low limit, for an alarm to be cleared (see Specify the Hysteresis - the Minimum Value Change that can Clear an Alarm in the ClearSCADA Guide to Core Point Configuration).
- Engineering Units Exceeded: Use to define how ClearSCADA processes an analog point’s value when the value is Over range or Under range (see Define how Over Range and Under Range Values are Processed in the ClearSCADA Guide to Core Point Configuration).
- Persistence: Use to determine the length of time for which a change in state has to persist before that change in state is recorded. Persistence does not apply if an analog point becomes over range (above Full Scale) or under range (below Zero Scale), as these states are reported immediately.
- Tune Limits: Use to define whether an Analog Point’s limits can be tuned (see Define whether an Analog Point’s Limits can be Tuned in the ClearSCADA Guide to Core Point Configuration).