Rockwell Automation FactoryTalk Historian SE ProcessBook 3.2 User Guide - Manual (Page 179)

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Visualize Data with Symbols
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Example 4: Comparing a Batch Run to a Standard
An engineer wants to compare sample measurements taken from one Batch
run and compare them to a fixed set of measurements he knows to be
desirable.
1. Select the fixed set of measurements by choosing the appropriate tag
or data set and indicating it is to be used for the X-axis.
2. Select the appropriate tags for the comparison batches, entering their
specific time ranges.
3. Use Recorded values for all retrieval mechanisms.
The data points are paired according to their position in the events list. The
XYPlot shows how closely the results are correlated by how closely the
pairs fall on a linear regression line. Pairs that fall outside this line may
indicate problems with the batch run.
Example 5: Comparing Two Time Ranges
An engineer wants to compare the performance of a Boiler unit over two
time ranges. He needs to determine whether a boiler's performance has
degraded over time or whether there are specific problems with the
equipment. To do this, he creates an XYPlot that compares the temperature
tag data from two different time ranges.
1. Type the tag twice and assign one instance as the X tag.
2. Type separate time ranges for each tag.
3. Set the match mechanism to be recorded or interpolated so that values
are paired by their position in the list.
If the pairs fall close to a linear regression line, you can assume the boiler's
performance is at least steady. If some pairs are far from the line, it may
indicate that the equipment has a specific problem.