Rockwell Automation FactoryTalk Historian SE DataLink 4.2 User Guide - Manual (Page 48)

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FactoryTalk Historian DataLink User Guide
40
Time Interval Type a time interval as a FactoryTalk Historian time (page 86)
expression. The interval is the sampling frequency used to collect or
calculate values over the course of the time range.
For example, an interval of 15m (15 minutes) returns a value for
every 15 minute interval.
Filter Expression Add a filter expression to filter event values using a mathematical
expression, eliminating data for which the expression evaluates as
false. The filter expression is applied to the raw data from FactoryTalk
Historian (and not values that result from the calculation itself).
For example, the simple filter expression:
sinusoid < 70
would remove all values over 70 from the calculation. You can also
use any valid PI performance equation in the filter expression to build
more complex expressions to remove atypical peaks in data values,
for example.
Select mark as filtered to substitute
Filtered as a placeholder for
each value or block of values filtered from the array based on the
filter
expression (page 91).
Special Notes You can use a FactoryTalk Historian Expression (page 91) instead of a
tag name for this function.
Reference a range of tag names to display sampled values for each.
Note that by default, values are displayed in rows for a column of
referenced tags, and in columns for a row of referenced tags.
The PISampFilDat() function is used if a filter expression is specified;
otherwise, the PISampDat() function is used.
PIExpDat() is used if a PI Expression is substituted for a tag.
Example:
To see periodic, interpolated values over the previous 24 hours for the
sinusoid tag, the following arguments are set for the Sampled Data
function:
Tagname = sinusoid
Start Time = -1d
End Time =
Time Interval = 3h
show timestamps
column