According to the program description
in this lab, we need to manipulate data
coming from measurement instruments through
calculations. Once we do that,
we are going to store that data in the PI Server
so that everybody will have access to the same
results, the same data.
In order to perform our calculations,
we will be using different
frequencies of calculation or
scan classes, and we want to make sure that those scan classes
are available on our
server. In order to check for that, I am
going to go to the PI,
Bin Directory, under the C: drive
where I am going to find
the --
let me go ahead and expand this --
pipeschd.bat.
I am going to right-click and
edit that file to take a look
and
see what scan classes are available.
The scan classes are
shown here in the last line.
We can see that there are three different scan classes:
the first one, which has a
frequency of one minute; the second
has a frequency of two minutes; and the last
one has a frequency of 30 seconds.
All of them will calculate
the Performance Equation on the hour
because the offset is zero.
Now that we know
that these scan classes are available, let's go ahead,
let's go ahead and go to the System Management
Tools and create the Performance Equations.
In here
we are going to go to Points,
and Performance Equations.
We click on New, and we can
go ahead and enter the information
as it was provided in the
Lab Manual. The name of this first
Performance Equation is going to be
CDT158.
Avg.
The Description
is going to be the average of
CDT158
over
two-minute periods.
And that's the frequency at which we are going to
compute this calculation.
Next, we want to make sure that we
have a Float32 Point,
that the PointSource is C:, that the
Engineering Units are in Degrees Celsius,
and now we are ready to move on to the next
tab, the Equation, where we can go ahead
and enter our PI Equation of Tag
Average, in-between parentheses,
CDT
158,
between single quotes,
and we are going to calculate the
average of the tag in-between the times
of two minutes ago --
so that's Now minus
two minutes -- and
Now. So, the
time
period is a two-minute time
period.
Next, we can go to the Scheduling Tab,
and in here we want to
set this up for a Scan Class
#2. As it was mentioned before, we have three
scan classes available. The Scan Class 2, as you
remember, was the one with a two-minute frequency.
We go to the Archive
Tab, and in here we want to make sure that the
Zero Value is going to be zero, that the
Span is going to be 150,
and that our Typical Value is
50.
We also want
to ensure, according to the directions, that Compression is
On, and
that the Exception Deviation is
zero, and the Compression Deviation
is zero. At this point,
we are ready to save this Performance
Equation, so we can click on the Save
Icon, and at the bottom we
can see the log that says that the
Performance Equation was successfully created.
Now we can go ahead and create
the next Performance Equation by clicking
on New, go into the
General Tab. We are going to
enter the name now of BA --
oops, sorry --
Status.1.
And the
Description of this Performance Equation
is going to be the Status
of the Batch
Reactor. Again, we want to make sure
that the Point Type is String, in accordance
to the directions, that the PointSource is C,
the Engineering
Units, we are going to leave that portion blank,
and the Equation that we are
going to enter is provided
in our manual. We are going to
concatenate
the Digital Text
from, between single
quotes,
CDM158
and the Text
[typing]
of space
and the
tag BA:
PHASE.1.
Again, in-between single
quotes.
We go to the Scheduling Tab, and we are going to
schedule this as a
Event-based Scheduling with the
Event Tag being the
BA:PHASE.1
Tag.
Under Scheduling, also, we want
to make sure that the timestamp
of the resulting expression is set to
the time when Expression is evaluated. This
can also be checked under Classic.
Location3
is zero. So we are now ready to
save our Performance Equation. We check
our Logs, and we ensure
that the Logs
state that the Performance
Equation was successfully created.
And now, we click on New, Performance
Equation, for our last one which is
going to be the
BA:ETHYLENE_
Volume.
[typing]
The Description
is going to be the volume
of Ethylene
produced by the minute.
The
Engineering Units are going to be
Cubic Meters. We want
to ensure that the PointType is Float32,
that the PointSource is
C, and under Equation, we
can go ahead and create our Equation
which, according to the
Manual -- and let me go
back and look at the Equation that
is provided for us here.
As explained
in the Manual, this is the --
let me see, it's down here.
As we can see, we are going to use
the ideal gas law and
we have inserted some constants
into this equation, and that's what we are
going to type in here for
an Equation. So,
for CDP158
we are going
to times that
8.3144.72 --
and that's going
to be times
CDT158
plus
273.15
divided by
28.05
times 200.
Next
we go to Scheduling. We want
to make sure that the scan class
is one for
a one-minute Scan Frequency.
We go to Archive, and we want to ensure
that the Zero Value's at zero, the Span
is set to 300, and our
Typical Value is 50. We also
want to use an Exception
Deviation of .1 and a Compress...
Compression Deviation of .2.
Now that we completed these Equations,
we can go ahead and Save the Performance
Equation, and we can see that it was
successfully created. Now,
an easy way to check on these Performance
Equations and ensure that they are actually
calculating the data and producing
data, is by going to the Archive
Editor, under Data, and
performing a Search for the
Performance Equations that we created. They all
had a PointSource of C. So,
PointSource of C, we do the Search,
and at the bottom of the list we
can see the three Performance Equations that
we created. CDT158.avg --
let's double-click on that, and we can see that it,
it has been calculating
the Average Value every two minutes.
We can go back
to our Search, and check
on the BA:STATUS which is the
Batch Reactor. We still do not have
any data there. Let's go ahead and check on the
last one which is the Volume of Ethylene
produced, and I still do not have
any data on either one.
Let's go back and make sure that our
Performance Equations have
no errors in them.
By going to Points,
PointBuilder, we can
do a search for our tags
in here, and
the tags, the BA:
STATUS, we can check on the Equation,
make sure that we typed that
in a correct format which is the
concatenation of the
Digital Text of CDM158
plus the -- a space,
and BA,
or Batch Reactor PHASE 1.
Let's go back to the Archive Editor
and see if we have any data
so far. We can see that our
Ethylene Volume Performance Equation has
already started producing some data,
and let's make sure that we also have data
for the STATUS of the Batch Reactor, and
we have data.