Let us identify the differences
in using the explore versus compare
functions in PI DataLink to build reports
based on event frames. These
events functions were added to PI DataLink
starting with PI DataLink 2014.
And in a previous video, we saw how to
use the explore function to create
reports. And this brought up the question,
when would you not use the explore function
and instead use the compare function.
The answer depends on whether or not you have
child event frames. If you do not have child event
frames, just stick with using explore.
So child event frames,
also called child events are used to
break down events into sub events that
have different stages. Say different parts to a
process, a root cause for a downtime
event. Child events therefore have to be associated
to a parent event. In this
example, I am looking at mining
trucks that are making round trips. And each
round trip has
different stages that
are child events.
There is a waiting for loading phase,
a loading phase, running loaded, unloaded,
and running empty.
And again these are all setup as child events.
If you want to look at child events grouped in this
type of hierarchy along with the associated parent
event, just like it is shown here in this
report, you will use the explore function.
Let us take a look at the configuration for this.
I am going to
do a left click to select and bring up
the explore events options that were chosen.
And we looked at how to configure this
to do a lot of things in the previous video.
But specific to child events,
we want to bring your focus
to the preview right here.
We can use the preview to look at the
hierarchy of the events and determine
are there child events and how many levels of
child events there are.
I can use the plus sign to expand
and we can look at the child events
and see that they are all one level below
the parent event.
To have them returned grouped in a
hierarchy, the only option that I will need
to do is to specify the number of child
event levels down here. You can see that the child
event levels were selected as one. Previously
when we were looking at things that did not have child event
frames, we left it at the default of zero.
So this allowed us to look
at the events in this hierarchy
a parent with children below it.
But what if I only want to focus on the
impact of a particular child event on
the parent event. For example, I have heard
that the performance during the running loaded
phase has the biggest impact on
the entire round trip meeting
the expected duration. Now this is something
to investigate. I do not really need to
see rows of all of the other child events.
I just need to focus on a specific
comparison. In order to do this, I am
going to use the compare function. And I have an
example of what that looks like right here.
In this type of report, I
use the compare function and now
for each parent
event, there is only this one single
row as before but information
that is about the child event
is listed here
right along side that
of the parent. So you can see
the information is presented on a
single row and you can tell what information is
coming from the parent event as opposed to which
information is coming from the child event
based on the syntax that is used.
So right here, you can see that this is denoting that
it is the parent information versus if it is
coming from a child event, you will see this type of
syntax where it is indicating that this is a
child event specifically
the running loaded child event.
And now that I have the information
organized this way, side by side on a
single row, the quick visuals that I have
added show me right away that there is not a complete
correlation between good performance and this running loaded child event;
and meeting the performance
requirements for the road trip parent event. As a
next step, I would do analysis to study the correlation
using an XY plot in Excel.
And I could make one of those very
easily because the data is already in the right format for me to do that.
Let us quickly
take a look at how this can be
setup. First, I will need to select
a cell where I want to start my event list.
So I have got B5 selected.
Then, I will choose the compare
option.
And the database looks good and
I will use my cell references having
the start time be this
cell reference and the end time being this
cell reference because I want to focus on looking at the
round trips that occurred yesterday.
And I want to look at the round trips that
specifically occurred
so I am going to need to select my
template, the truck roundtrip template.
And the only other option that I am going to
choose is I want to focus on
under more search options, search mode,
only the events that were entirely in the range of yesterday.
Now in my preview, I see
that same type of view which is
reminding me this is exactly my
parent. And these are my children.
I will keep scrolling down.
You might have noticed
that all of these options that we are choosing for the
compare events, those were the exact same options that we
chose in explore. In fact, the options
are all basically exactly the
same until you get down here to the bottom.
Before, in addition to having the
output cell, there was a specific
option, another one, about choosing the child
event levels. And this is not included
for compare because we are bringing everything to the single row.
Additionally,
as I am looking at all of the
potential columns to display,
I am going to reduce this down and look at only very
specific ones for the parent that I am interested in.
And if you look down on the list, you can see
that these are only the ones for the parent.
But I want to bring in the attributes
from that specific child event, the running loaded view.
How can I do that? To do
that, I am going to use this button
right here. And this is going
to bring in the possible attributes that I can
add and I can start to see through the
hierarchy, I can pick the ones that I am interested in.
So I am going to go to running loaded and I am going to be
bringing in the duration,
the engine RPM, and the driver.
Those are the fields that I want to compare.
Then I will hit OK.
You can see this is the same thing that we were looking at
earlier, bringing in those
attributes that are specific to the
parent and those attributes that are specific
to the child on a single row for quick comparisons.
To conclude,
this is really the difference between the explore and
compare functions. The formatting for how a child event
information is presented.
Plus if you do not have child events,
just use the explore function. If you do
have child events, make the choice
and choose explore for the hierarchical
tree format and compare for the
side to side format of your child events.