Classic event subsystem

Plant events range from startups and shutdowns, through trips and shift changes, to batch events and operator actions.

You can use the AVEVA Historian Classic Event subsystem to detect events and associate actions when they are detected. At a basic level, anything that can be determined by examining stored data can be used as an event. The Classic Event subsystem can be configured to periodically check to see if an event occurred. This is called event detection. A subsequent action can then be triggered after an event is detected. However, there is no guarantee of immediacy for actions; in fact, other mechanisms can preempt actions under certain circumstances.

For the Historian, event storage encapsulates more than just the fact that something happened. An event is the set of attributes describing the moment a detection criterion is met on historical tag values in the Historian. Attributes of an event include the date and time that the event occurred in history and the date and time that it was detected. Records of detected events can be logged to the database regardless of whether or not any configured actions are subsequently initiated. In other words, sometimes it may be desirable to simply log the fact that an event occurred without initiating an action. The opposite may be true, as well.

In short, the Classic Event subsystem performs the following basic functions:

• Detects when events occur by comparing sets of criteria against historical data in the database.

• Optionally logs event records to a dedicated SQL Server table (EventHistory).

• Optionally triggers a configured action each time an event is occurs.

For information about configuring events within the Classic Events Subsystem, see the Configure classic events.

The Classic Event subsystem does not support Daylight Savings Time changes. The Replication subsystem, however, does handle Daylight Savings Time changes, and you can use replication to generate data summaries according to a schedule. For more information, see Manage and configure replication.