How it works
The OPC DA server supports OPC data access with the following specifications:
● 1.0a
● 2.0.
● 3.0.
The OPC DA server is a DCOM application. Using this software interface, the OPC DA server
provides the OPC DA client with the necessary information about PCS 7 OS tags. The OPC
DA server becomes active when it is accessed by the OPC DA client over a connection to the
OPC DA server.
6.4 OPC Historical Data Access (OPC HDA)
6.4.1 Overview
Overview
You will find information about the following topics in the chapters below:
● How the OPC HDA server works
● Data structure of the OPC HDA server
● Overview of supported attributes
● Overview of supported aggregate functions
● Overview of supported functions
● Time format of the OPC HDA server
● Quality codes
The following chapters show the data structure and the attributes, aggregate functions and
functions supported by the OPC HDA server. This is not a detailed description but rather an
overview. Detailed information is available in the "OPC Historical Data Access Specification"
of the OPC Foundation.
6.4.2 How the OPC HDA server works
How it works
Using OPC HDA, it is possible to access archived data from the PCS 7servers. The OPC HDA
server is a DCOM application that provides the OPC HDA client with the required data from
the PCS 7 OS archive system. Data is accessed via item handles. Only read access to archived
data is approved for PCS 7. The data can also be analyzed.
OpenPCS 7 interface
6.4 OPC Historical Data Access (OPC HDA)
OpenPCS 7
48 Function Manual, 05/2012, A5E02780178-02
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