User Manual

Operating Reference
Trends
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Name Description
1
Report Defintion
Selection
Location of Report Definitions and Report folders in the Application View of
System Browser.
2
Automatic report
execution
Runs a Report Definition in the background.
3
Report Definition
Properties
Properties (Last Run, Summary Status, and Show in Related Items)
displayed in the Extended Operations tab.
3.6 Trends
The Trends application allows you to work with trends that are recurring samples of
data. These data samples can be taken at regular time intervals or whenever there
is a change in a value of an object by a prescribed amount. Some examples of
data samples in trending include the following:
● Collecting the room temperature after every 10 minutes.
● Sensitivity reading of smoke detectors once per week.
Trends are of two types, online and offline. Online trends [➙ 309] record real-time
values from your plant and display them graphically in a Trend View. Offline trend
[➙ 307] data is used for the longer-term storage and retrieval of historical data for
the analysis of entire plants or single processes.
You can add, modify, and delete values of trended properties of trended objects
that are logged in online as well as offline trends through the Manual Correction
application.
You can use Trend Views in two ways in the management station:
● During operation, trend data recorded in real-time and saved to the trend
database (management station is online).
● Trend data is recorded in the automation station (management station is
offline) and periodically loaded to the management station trend database.
● You can display the trend data in the Trend Viewer any time, even if the
management station is not connected to the site (no real-time data available).
The Trends application is covered by a license. In order to access the Trends
application, you must ensure that the Trends license is available in your system.
Record Trend Data
You can record trend data using either of the following methods:
● Change-of-value (COV)
The change-of-value method allows you to record new data when the data
point value changes. No value is recorded or transmitted if the value does not
change over an extended period of time. Database acquisition of several data
points in a Trend View is asynchronous.
● Interval-based
The interval-based method is applicable to record offline trend data. It allows
you to record current data as soon as the timestamp is reached. The data
values are recorded without impacting a defined COV property.