In this video, I'll be introducing you to the PI
Interface for OPC DA. I'll explain how
data collection works. I'll give some
architecture recommendations and finally I'll
enumerate the different steps that you need to accomplish to install and configure
your very own PI Interface for OPC DA.
The PI Interface for OPC DA
is used to collect data from an OPC DA server.
But in order to understand what an
OPC DA server is, we first need to understand what
OPC DA means. OPC stands
for OLE for process control. DA
stands for data access. So OPC DA
is a standard to communicate data across automation systems.
So let's
take a step back. Here we have a bunch of
different vendors with different automation systems.
These systems are speaking different languages.
And the PI System also speaks its
own language. So these languages need to be
translated and people in the automation
industry came up with the OPC Standard. So
this is a standard way to expose
data on these systems.
And a standard way of collecting data on these systems.
So it's basically a standard that was
created to facilitate data sharing.
How does data sharing actually work using the
OPC DA standard? Well first we have our
data source.
And this data source is connected to an
OPC DA server. This OPC DA
server is collecting data off the data
source and exposing it using the OPC DA
standard. And it's making it available to
different applications. These applications are
called OPC DA clients. So these are
applications whose job it is to translate
the data from the OPC DA
standard into whatever protocol is
needed for their data sync. So basically
on the PI System, the OPC DA client is
the PI Interface for OPC DA.
And the data sync is the PI Data Archive.
So the OPC DA Server once again is translating
the data from the data source
and the PI Interface for OPC DA
is translating the data from the OPC
DA Server for the PI Data Archive to be able to accept
it. And once the data reaches the PI Data
Archive, it can then be reached by various different
PI clients. So at this point you might be
wondering where do I install these different
components? Well, you have a couple of different
options. But what we recommend is to install the OPC DA
Server and the PI Interface for OPC
DA on the same node. This greatly
facilitates the installation
process. And it also reduces the points of failure,
since both of these are on the same node. However,
it is possible to install the
OPC DA server and the PI Interface
for OPC DA on different
nodes. However, this will require an
additional step of configuring DCOM security.
This is important to keep in mind.
So those of you who are a bit more familiar
with the PI Interface for OPC DA, might recall that we
also have the PI Interface for OPC
HDA. And you might be wondering why
you would use the PI Interface for OPC
HDA or the PI Interface for OPC DA.
Well, these are simply different
protocols for different
standards for the OPC standards. So as we know,
DA stands for data access whereas
HDA stands for historical data
access. So an OPC server
might be either OPC DA or OPC HDA
compliant. So OPC
DA means that the OPC server is going to be
getting real-time data. So data that is going to be
updating on a periodic basis.
Whereas an OPC HDA server would have a
bunch of historical or archived
data. And the OPC HDA
client would be getting all of this data
at once and sending it to its data sync. The
quick answer might be, if your
OPC server is OPC DA compliant,
then you would use the PI Interface for OPC DA. And if your
OPC server is OPC HDA compliant,
then you would use the PI Interface for OPC
HDA. But a lot of OPC
servers can actually be used
for both OPC DA and OPC HDA. So
a better answer would be, it depends what kind of data you want to
collect. If you want to collect real-time data,
so data that's going to be updating periodically, then you'll want to use
the PI Interface for
OPC DA. So next question, let's say we
have a bunch of different
OPC DA Servers. We have multiple OPC
DA Servers. Do we need to install the PI Interface for
OPC DA multiple times? No. All
we need is a single PI Interface for
OPC DA installation and we need to configure
multiple instances of the PI Interface for
OPC DA. To do that, we need the
PI Interface Configuration Utility. And even if you only have the
single OPC DA server, you'll need the PI Interface
Configuration Utility. Since this is the GUI
that's used to create instances
of the PI Interface for OPC
DA. And to configure them and to also to maintain
them. So you'll need to install both of these
components. OK, so we've gone over all of
the basics. Now what are the steps that we are going to need
to go through? So the first
step is going to be to install the PI Interface
for OPC DA and the PI Interface Configuration
Utility. Next, we are going to need
to make sure that our OPC server has a
good status and it has data updating.
And we'll do this using the PI OPC
Client Tool which is installed when you install the PI
Interface for OPC DA. Next, we'll want to
configure a new instance of the PI Interface
for OPC DA using the PI Interface Configuration Utility.
Then we'll want to create PI
points to collect data from the OPC server.
And finally once we've done all of that,
we need to make sure to configure buffering with the PI Buffer
Subsystem to make sure that if
ever, our PI Interface for OPC DA losing its
connection with the PI Data Archive, it
will be able to continue collecting data and
buffer this data. So in the upcoming playlist,
I'll be showing you how to complete all the steps
required to start collecting data from an OPC
Server. And once you've done that, you can check out our
PI Buffer Subsystem playlist in order to learn how to configure buffering.