Section 8.1,
Interface Installation.
Here is what we would suggest you do to install
an interface. Here are typically the steps that are taken when
installing an interface. First thing you do is install the
Operating System. It's not unusual to have a brand new
computer and we are assuming that this is going to be some sort of remote
data collection nodes. So it's probably not a massive
$25,000 computer. It does not
really need the kind of hardware overkill that you'd find in a PI Server.
In fact nothing of consequence
is generally ever stored on there. All you
really need is a fast network card and enough
CPU resources to run the interface.
You can spend your big money on the
server, that's where you are going to need things like RAID
arrays for a backup etc. So anyway you
install the Operating System on this new machine. Make sure
you check the time and the time zone. That's a
tricky thing if you have not done that before.
Let me describe this. You go into the
Control Panel and look at date and
time. People generally get the time
right and the day. But in many cases they
get the time zone completely wrong. And
that is going to be real bad news on a system like
PI. PI as you might guess since it deals in realtime
history, it is very dependent on proper
time zone settings. Just to give you an example,
one time we had a user that bought a computer
in New York City, took it back to Singapore and set it
up, changed the date and time but forgot to change the time zone.
So here is now a computer that is
sitting in Singapore but the computer thinks it's sitting in New York City.
And of course what happens is since we
store everything using Universal Coordinated Time,
or so called Greenwich Standard Time,
then we internally store
data with the wrong time off-sets.
So install the Operating System, check the time and the time zone.
You then install the data source.
Now that's only if that data source is on the same
computer as the interface.
Sometimes that happens,
for a lot of UNIX boxes, we see the main machine interface
from the control system is actually on the same computer.
Whether it is installed or
not on the same machine, at some point you need to
test the connection with that data source.
You cannot go any further with our tests until the local
utilities from the vendor of the control system
or the vendor of the data source
unless their utilities can connect
across the network, there is no point in going any further.
So using the vendor supplied
utilities, you test your connection with the data source.
You then create a PI Trust on the PI Server.
Probably the same most common mistake-- people always forget
to do that. Typically what happens is we try to
write data to the PI Server
from the interface and get a -10401 error.
Unable to write
because there is no permission to.
So create that PI Trust as we described in the previous chapter.
You then install the PI SDK and the PI API will be installed as well
The SDK stands for Software Development Kit.
API stands for Application Programming Interface.
These are basically different vintages of the same type of thing.
The low level software that is required for communication
between the PI Server and the Interface node.
Once that is install, you then test the
connection with the PI Server and I will show you some utilities to do that.
We installed the interfaces. One thing
that's not listed here and probably should be
is to install and configure the interfaces.
No interface typically just runs straight out of the box. There
is usually configuration involved.
And then a very good last step, it is optional
but we highly recommend it, is you configure data
buffer service. You basically configure
the buffering
on that Interface node such that if the
Home node fails, we start to buffer on that Interface node
on that remote data collection node.
So this is the big picture and
we will go through each of this in greater detail as we go through the class.
When you install an interface
it's going to go into Program Files,
PIPCInterfaces directory.
And so let's take a look at that directory.
Here is my Interface
node and as you can see I am in
Program FilesPIPC. You see an interfaces directory
and that interfaces directory has an
OPCInt sub-directory. That's this particular interface
we are using in this example-- the OPC interface.
So if we look at this whole
interfaces directory, there are
all the different interfaces
we have used as different examples in our
training are listed here. Typically you do not find
that many interfaces running on a typical
PI interface node.
We have a lot that we use in different examples in our webinars etc.
Now this OPC interface is going
to have... For all of our interfaces
they are going to have an executable file. And
it's also going to have a batch file that
is used for storing the switches that are used during the
start-up of the interface. So you will find an executable,
a batch file. The batch file is
going to contain
among other things, it's going to contain
all of the parameters that are used
in starting up an interface. These parameters
are generally delimited with these slashes.
Now let's take a look at the
interface for the
batch file for the OPC interface.
We will take a look at this one right here.
We will right click and choose edit.
And this is kind of over kill
if I edited this a lot.
These are the set of switches that are currently in place.
All the others here have been remarked out
by using that REM statement.
So take a look at the little switches here. These tell me the
name of the server. This tells me the name of the
OPC data source etc.
So all of these switches control the
execution of the interface.
That's really kind of over kill.
So let me show you one
that is not quite so detailed. Here is a much
more limited example and much more
straight forward example that you will find at the bottom of your
notes in the book. This is the executable, and these are the
different switches that are being used within that batch file.
They pass different switches like the name of the PointSource,
the name of the Interface ID and things like the scan classes.
Now that's not the last we are going to hear about these
switches. In fact we spend a great deal of time discussing
these switches later on. And we can
learn more information about these switches.
Now in addition to the batch
file, you will also find a documentation
file and that's where you will find the actual interface documentation
that ships with each interface. And we strongly
suggest you read those interface documents for details
on how to configure certain
location codes which we will discuss later on.
And there is also a text file that tells you
more about the version of the interface that you are currently working with.
Now these batch files, as I
said, they contain the configuration information.
And anything that you change in those start up files are not
affected until the next time you start and restart the interface.
It's really one of the few things in PI that
does not update automatically. You do have to stop and restart the
interface. As you might guess, we do have a better mechanism
to manage this batch file than simply opening
up a text file using Notepad.
We have something called the Interface Configuration
Utility that can be used to manage that batch
file and we will look at that later.