OPC Classic HDA Aggregates

In the OPC Classic HDA server, an aggregate is a function that is used to process raw data from an OPC Classic HDA server over a given range of time divided into discrete intervals. These aggregates can be further used to for various purposes, such as visualizing the trends in the data.

The standard aggregates supported are:

  • Minimum
  • Maximum
  • Average
The custom aggregates supported are:
  • Nearest
  • Before
  • After
  • GE Interpolative

Consider the following as a Historian Source for the Minimum, Maximum and Average Aggregates:

TimestampValue Quality Notes
Jan-01-2002 12:00:00 0No Data First archive entry Point Created
Jan-01-2002 12:00:10 10Raw, Good
Jan-01-2002 12:00:20 20Raw, Good
Jan-01-2002 12:00:30 30Raw, Good
Jan-01-2002 12:00:40 40Raw, Bad Scan failed, Bad data entered
Jan-01-2002 12:00:50 50Raw, Good
Jan-01-2002 12:01:00 60Raw, Good
Jan-01-2002 12:01:10 70Raw, Bad Value is flagged as questionable
Jan-01-2002 12:01:20 80Raw, Good
Jan-01-2002 12:01:30 90Raw, Good
NULL No Data No more entries, awaiting next scan.
Consider the following Historian Source for Nearest, Before and After Aggregates:
Timestamp Value Quality Notes

Feb-28-2002

12:01:30

987Raw, Bad

Mar-01-2002

12:01:30

98765Raw, Good

Mar-02-2002

12:01:30

9876Raw, Bad
Jan-01-2002 12:00:00 0No Data First archive entry Point Created
Jan-01-2002 12:00:10 10Raw, Good
Jan-01-2002 12:00:20 20Raw, Good
Jan-01-2002 12:00:30 30Raw, Good
Jan-01-2002 12:00:40 40Raw, Bad Scan failed, Bad data entered
Jan-01-2002 12:00:50 50Raw, Good
Jan-01-2002 12:01:00 60Raw, Good
Jan-01-2002 12:01:10 70Raw, Bad Value is flagged as questionable
Jan-01-2002 12:01:20 80Raw, Good
Jan-01-2002 12:01:30 90Raw, Good