Uses for the classic event subsystem

Generally, you should use the AVEVA Historian Classic Event subsystem to monitor non-critical system conditions that occur only occasionally. For example, possible event detections that you can set up include:

• Detect all occurrences in history when the value of a discrete tag is set to 0

• Detect if the system clock is set to a specified date and/or time

• Determine the state of information in the database by a SQL statement

You can use event actions to perform tasks such as the following:

• Send e-mail messages to remind managers about weekly maintenance checks

• Summarize plant data to create a statistical analysis over defined periods of time

• Take "snapshots" of system data

• Modify storage conditions (such as time and value deadbands)

• Generally perform any database-related task

The Classic Event subsystem is not designed to transfer data to and from the database continually and should not be used in this manner. The only exception is for summary actions; the Classic Event subsystem can continually process data aggregates so that they are available for reporting purposes.

The Classic Event subsystem should not be used as an alarm system. An alarm system such as provided with InTouch HMI software can be used to alert operators to specific satisfied conditions. The InTouch alarm system is intended as a notification system to inform operators of process and system conditions promptly upon their occurrence. The InTouch alarm system supports displaying, logging, and printing capabilities for process alarms and system events. (Alarms represent warnings of process conditions, while events represent normal system status messages.) For more information on the InTouch alarm system, see your InTouch documentation.

In contrast, the Classic Event subsystem is intended to initiate actions based upon historical event detection. An alarm system presupposes an immediate message response is propagated for all configured alarms at the time the respective conditions are met. In this sense, the Historian Classic Event subsystem is not an alarm system. The Classic Event subsystem queues up detected events and processes them accordingly based upon preconfigured priorities.