Chapter 4
Installing and Using the FieldPoint Software
©
National Instruments Corporation
4-19
Follow these steps to start using the FieldPoint OPC server:
1.
Open the FieldPoint OPC server,
National Instruments.OPCFieldPoint
.
This server was registered with Windows when you installed the
FieldPoint software. OPC Clients should be able to show you a list of
available registered servers, but you might have to type this name in
yourself. The OPC client might automatically connect to the server
when you select it, but if you are given the option to explicitly connect
to the FieldPoint OPC server, you should do so.
2.
Create a group.
Groups are a collection of I/O items. Some OPC clients might not give
you the option of creating groups, or they might be created for you.
3.
Select the I/O Items, which you configured in FieldPoint Explorer, that
you want to read or write as a part of this group.
Many OPC clients can use the “Browse Address Space” feature of the
FieldPoint OPC Server to show you a list of all of the I/O Items you
configured in FieldPoint Explorer. However, if the OPC client you are
using does not support this feature, you might need to type the Item IDs
of the I/O Items directly. The naming convention of the FieldPoint Item
IDs is [
Comm resource name
]\[
Device Name
]\[
I/O Item name
]
where the Comm resource, Device, and I/O Item names are the names
given in FieldPoint Explorer. For example, an Item ID associated
with one of the I/O Items shown in Figure 4-1 would be
FP Res\FP-TC-120 @1\Channel 0
.
In most cases, the preceding steps are all that is required to configure an
OPC client to read from I/O items of the FieldPoint OPC server. In some
cases, the OPC client might require more information about the FieldPoint
OPC server. The following list contains additional information about the
FieldPoint OPC server, which you might find helpful.
•
The FieldPoint OPC Server does not require an
Access Path
. Some
OPC clients might expect the access path to be included in the Item ID
name or might request the access path when you select I/O Items. You
should be able to leave the access path blank (empty string).
•
The FieldPoint OPC custom interface is an out of process server.
•
The FieldPoint OPC Server supports both synchronous and
asynchronous reads and writes.
•
The FieldPoint OPC Server uses the “GetErrorString” method to
return error and diagnostic messages from the FieldPoint server and
hardware. OPC clients that do not support this method might only give
you error messages like “Bad, non-specific” along with an error code.