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Here they are again. These are our
Exception and Compression Attributes. They are all listed in one place here.
So, you can see, we have got, we have got Exception
Deviation Min and Max. We have
got Compression Deviation Min and Max. And if you take a look
at where they are in our, our PointBuilder here -- here's
a PI Tag, and if we -- see them right here.
This is our, our Compression and Exception Deviation.
The Default Exception Deviation is one
Engineering Unit. The Compr...Default
Excep...Compression Deviation is two Engineering
Units. They say I can show them
either way. But, those are the Defaults. And the
Default Max Time for the
Exception Test is ten minutes. The
Default Max Time for the Compression Test is eight
hours. So, if eight hours goes by and we do not store a value,
it passes the deadband, then we, we simply store the next
Snapshot Value that comes in. So, these are our
Defaults. You can see them all, you know, grouped together here
in one place. And, there is a, a
reason for caution when dealing with zero in Span
with some of our editing tools. If you are using
the -- or just keep in mind that if you are
using Percentage of Span --
if you have chosen, if you have chosen Percentage of Span
for how you are going to determine
Exception and Comp...the Exception Deviation and the
Compression Deviation, then, if you do change your
Span, that's going to have an effect on your Data Compression.
So, keep an eye out for that if you are making changes
to zero and Span, that will affect anything whose
values, for Exception and Compression, have been defined
as Percentage of Span.
Now one last thing I should mention is this
attribute right here called Step. As I described earlier,
Step has an impact on PI ProcessBook
by changing whether we see a stair-step function
or just connecting the dots in ProcessBook. That's the
effect it has on, on actually looking at the data.
But, it does have an effect on how the
Compression Test is done. If Step is turned on,
then the Compression Test simply turns into a, a
second type of Exception Test.
We do not account for Slope at all in the Compression
Test if Step is turned on. So, we simply do a second
Exception Test using the Compression Deviation as
the second value for that, for that test.
So that's what happens when we set Step Equal to On.