Okay, let's concentrate now on these different fields
on these different tabs within the ICU. We are not going to look
at all the fields, but the ones that, that make sense to look at.
First of all, we looked at the OP...or this Point Source already.
The Point Source of OPC here is going to map over to
the List of Tags on the Point Database
back on the PI Server that have that Point Source of
OPC. So, that's, you know, that's the whole purpose of this --
is to mate these two together so that when the Interface
starts up it's going to know which points, out of all the
millions of points you might have on your PI System, it needs to
start scanning. And, it does it by matching this Point Source here.
OPC, to this Point Source
that's defined right here. Now there's a problem that can occur
if you have got two copies of this same Interface that are running,
you know, within the same PI Server or PI System.
When you do that, you would probably just create
the one copy of the Interface
with a Point Source as OPC1 and the other
with a Point Source of OPC2. Let me demonstrate
here. So imagine this right here
is our, our Point Database
out on the Point Server, and I am
going to draw it like it's a table. So, here's a big table.
And every Tag has a Tag Name. It's got a,
you know, a zero and a span
and all the other things that you'd associate with a Tag.
And then, of course, one of the things that it has is this
thing called Point Source. So imagine we have got Tag 1
through Tag 3 million.
And,
with all these Tags,
you know, we need this, this Point Source here to identify which ones
to start scanning. So, if
Tag 1 is scanned by the first copy of the Interface, we would call that
a Point Source of OPC1. We would define it
in ICU as OPC1, and then when it
starts up it would look for any Tags that have that Point Source.
This Tag 2 might be OPC2.
This Tag 3 might be back to OPC1
again. Tag 4 might be scanned also by
OPC1. But, the point is, that as
you, as you bring these,
these things up and running, if they write any messages to the
Message Log, they are all going to be written with the
same Interface Name. They are all going to be written as, well, this is
on the OPC Interface. We really do not write
the Point Source into the Message Log so you are not really going to know
the difference between, you know, the Tags
whose messages are being written by this Interface
vs a different Interface, the other OPC
Interface. So what we have in that case,
we have another field. It's a field called ID.
Now that's not really the truth, and I will explain why I am
lying in just a second. But, it's a field called
ID where you have the choice to put up to nine characters
that helps you distinguish which copy
of the Interface is writing to that Message Log. So, for
example, I would probably just keep this consistent.
Say, okay, this is ID1, this is ID2,
this is ID 1, 1, 2, etc. So that
the ID that you, you know, that you
associate with each Interface, and that is something you will put in
ICU. You will configure what its ID number is,
so that that's going to be written into the Message Log.
Now I said I was lying and, and that's because
this really, in the Point Configuration it's not called
ID. It, it is called ID in
the Interface Configuration Utility, but in
the Point Configuration it's actually called Location
Code 1, or you will see it abbreviated Loc1
in some pla...in some manuals. So it's Location
Code 1 in the Point Configuration that gives you
this opportunity. So, it
is not an issue that if you are writing to the Message Log
it's through the use of this ID in ICU
and through Location 1 in the
Point Figuration that you would distinguish one
Interface from another for purposes of,
of writing those messages to the Message Log. Now,
there is an exception to that rule, and the exception is
for older Interfaces. Let's say we have got some
old Interfaces that have a Point Source of,
oh, I do not know, let's say "H." Let's
say these, these Tags have a Point Source of "H"
and this is from an Interface that, for some reason,
either because of the age of the Interface or just because of the,
the platform we wrote it on, whatever -- it's,
it's a Point Source that cannot have more than
one character. We actually have some Interfaces that are like
that. Well, that can be a real problem
because, let's say, you have got more than one of
these Interfaces. Yeah. Let's say that,
you know, this Tag right here, whatever Tag this might be, Tag
Number 15 or whatever. That Tag
15 is actually on Interface
Number 1 of that
"H" Interface Point Source, and this
Tag 16 is Interface Number 2. Well,
you cannot do that. As I said, some Interfaces just
will not permit that. You are not permitted
to use more than a single character in its Point
Source. So, how do we handle that? Well, that's where
this ID comes in to the rescue here.
What we would simple do is put in the
ID number in Location Code 1 for the
Point Definition. So, we would define an ICU
that this is -- okay, this is the "H" Interface
with a Point Source of "H" and the ID of one.
A second Interface of the same
type, that has the same Point Source, would be identified as a
ID of two. And, in that way,
when we launch that Interface, it's going to know
by looking at this Location Code 1 up here, it's
going to know which Tags go with which Interface.
So that's how it looks conceptually.
Let's take a look at the actual ICU.
Back in ICU
of course Point Source is here. ID
is right here. That's where you would specify the Interface
ID. So, using my example,
I am not going to change this. But let's say this is one of those
Interfaces that only supports a single character for it's Point Source.
If, if you have got more than one
running, you are going to have to name one of those Interfaces,
Interface ID1 and the other one Interface ID2.
And then when you configure your Tags --
again, let's pretend this is one of those Tags -- you would
put an "H" here for the Point Source and then it's all
the way over here in the Classic Tab, that's where you would change
Location Code 1. You'd make that either a one,
or a two, depending on which copy of that
Interface it's associated with. Now the last thing I want
to mention about this is the Scan Classes. If you
recall, Scan Class is that slash F Parameter.
And, this is where it's configured. It's on the front
page. So, again, if you need any more information
about any of the switches that you see
here, you know, just go to this, this is the UniInt
User Guide. You will find it in the Download on our
website or you can find it in the class materials.
Anyway, this UniInt Interface Guide has this
section on Start-up Parameters. So just
about anything you want to know about -- like, for example, that
ID equals. You know, if I want to know everything about
ID equals, the fact that I can use
it, you know, for these two different things -- that's described
in this UniInt Document.