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2.1
Introduction to the PHD OPC Server
The PHD OPC Server is a Uniformance component that implements OLE for Process Control
(OPC) interfaces as a method of access to a Uniformance Process History Database (PHD)
Server. The interfaces enable client applications to access a single Uniformance PHD Server.
A Uniformance PHD Server stores variable data from a variety of process related sources. All
data values stored in a PHD Server are maintained over time in history archives. The PHD
Server provides interfaces through which clients may access the current or historical values
from its storage.
The PHD OPC Server is an independent executable program – it can reside on the same
machine as the PHD Server or on a remote server.
The OPC standard interface specifies a standard set of interface semantics for access to data
values. The PHD OPC Server is compliant with both the OPC DA and OPC HDA standards,
described as follows:
OPC DA
OPC HDA
Supported OPC standards
The PHD OPC Server is compliant with the following OPC standard versions:
•
DA Versions 1.0A, 2.05, 3.0
•
HDA Versions 1.1, 1.2
2. Getting Started
The OPC Data Access (DA) standard interface allows clients to gain
access to real-time (current) data values maintained by a PHD Server.
The OPC Historical Data Access (HDA) standard interface allows clients
to gain access to historical data values maintained by a PHD Server.
Uniformance - PHD OPC Server User Guide • 11
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