We have mentioned a couple of times PI Tags.
We did Tag searches where we went out and found Tags.
And then we actually looked at some of the attributes of Tags
using this Point Builder. But what is a Tag?
Well, as you can see, a Tag as attributes, but, you know, that's not what
you are interested in. It's like the old saying, when you buy a drill,
you do not want a drill, you need a hole. Right?
Well, it's like that with PI Tags. When you create a Tag
you are interested in a Tag, not because of its
attributes, but because of the data that you are going to store
in that Tag. So, let me go ahead and bring up a copy of
Excel. This copy is using the DataLink
Add-in to retrieve some Tag Values from the PI Server.
So, here's a Tag called CDT158. That's its Tag
Name. It's a Real, as you can see.
We are bringing in real-time data. Here's the Timestamp, here's the Values.
That's what you create a Tag for. So that you have a history
of the data. We have Integer Tags.
We have something called Digital Tags where we have digital
states. You know, finite number of possible
Values there. So, you know, first and foremost,
a Tag contains Values. So, one of the,
the most important attributes of a Tag is that it contains
Values in the form of Timestamps and Values. So, that's the
history that goes with a Tag. Now this is a real good
time to remind you that we do have other
ways of finding Tags than that Tag Search. In fact,
the best way, the premier way, the way we are asking everybody
use in the future, is to use our
asset framework called PI AF. This is the PI
System Explorer. You can see, through the PI System Explorer,
I can traverse through a hierarchy to find
individual pieces of equipment like down here in Production in this mixing
room, I can find a pump.
And, this particular pump has certain attributes
hanging off of it, and one of those attributes is a
PI Tag. So, a PI Tag can be
found using AF. A PI Tag is a
data reference for AF. So, you know,
when it comes to finding what you are interested in, you
can use Tag Search but you can also use AF, and that's what we
strongly suggest. There's a Search mechanism within here as well.
And, in most cases, the destination
for this search is going to end up being a PI Tag.
As you can see, it's the same PI Tag we were looking at before.
At
PI Tags have certain naming conventions. I am just going to bring up
your class material for a second. And, if you are interested
in what the naming conventions are, you know, here's, here's a
list of the, the characters you cannot use.
You know, here's some things we suggest you might want to use. But, of course,
naming conventions, like any naming convention, they are up to
you, so we are not going to go into a lot of detail on that.
But that's where you'd find more information.
Now, one of the attributes of a PI Tag
is something called its Point Class.
So, here's some PI Tags, existing PI Tags.
They have Point Classes of
classic. And, the classic Point Class has certain
attribute sets that are common across that Point Class.
Now, when you create a brand new
PI Tag -- let me go ahead a create a new one here --
I will just call this Test.
As you can see, you can choose one of these five different
Point Classes. Now, the only ones you will typically be using
are going to be classic, and maybe, rarely,
a base, when you are creating just regular PI
Tags. If you are creating special purpose Tags like
Totalizers or SQC Alarms or
Traditional Alarms, then you can choose these other Point
Classes. And, when you do make that change to the Point
Class, you will notice a different set of attributes appear.
So, when I go to Alarm, for example,
we see there are some Alarm attributes
that you can change. Totalizer's
another Point Class. As you can see, it brings up
all different types of attributes that are not in the regular Point Class, the
classic Point Class.
Now the base Point Class is rarely used. It's a Point Class
that's used for things that are not getting their data
from an instrument system, from a traditional interface.
So, as you can see, some of these classic attributes
are not, they are not supported with the base
attri...or the base Point Class.
So, for the most part, you are going to be using classic Point Class.
That's the default. If you do not change it, that's what you are going to get as a
PI Point Class. Now, this Point Class
List is actually extensible. You will notice,
for example, if you are using PI Com Connectors, part of the
installation of that is going to be to install a new Point Class,
so that you will see a, a new Point Class here that you would use
for Com Connector Tags. And when I say it's
extensible, it's not just OSIsoft that can extend it.
These can be user-defined Point Classes as well.