Rockwell Automation FactoryTalk Historian SE ProcessBook 3.2 User Guide - Manual (Page 282)

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FactoryTalk Historian ProcessBook User Guide
264
The selected data set/column(s) is now listed under Tags in Plot in the
Define Trend dialog box.
8. Select tags as desired and format the trend. If you wish to see or edit
the definitions of placeholders, click Custom Placeholders in the
Define Trend dialog box.
9. Click OK. Data is displayed on the trend.
If you select the Description check box, on the Display Format tab in
the Define Trend dialog box, then the description of the data set is taken
from the PI Calculation Data dialog box and repeated for each column that
is plotted. There are usually no engineering units for a data set column.
Time Intervals for Plotting Tags and Data Sets
The Start and End plot times on the Define Trend (page 110) dialog box
are used to determine the time range for plotting tags. However, a data set
may have different time boundaries than the plot time start and end for the
tags. If the time range for the data set starts later than the time range for the
tags, the data set traces begin with X marks.
Refresh a Trend Containing a Data Set
In a display containing only data from data sets, the data is refreshed based
on the Data Set Refresh Interval, which is configured in the data set. The
trend does not update again until the Data Set Refresh Interval has expired,
at which time it requests another set of values and redraws itself. A
FactoryTalk Historian tag in a display, on the other hand, receives
exception notifications from the FactoryTalk Historian system and is
updated on the display whenever the polling period elapses (every five
seconds by default).
If both FactoryTalk Historian and data set data are to be plotted on the
same trend, then the latest data set value is continued toward the end time