About OPC Classic HDA

About OPC Classic Historical Data Access (HDA)

OPC Classic HDA is widespread standard, which provides specifications to retrieve and analyze historical process data. This data is typically stored in a process data archive, database, or a remote terminal unit (RTU). You can analyze this data for trending, fault prediction, performance assessment, and so on.

Advantages of Using OPC Classic HDA
  • With OPC Classic HDA, the exchange of historical data between an application and any data archive is consistent. Therefore, OPC HDA client applications that implement trends, reports, or spreadsheets can retrieve historical process data from Historian and other OPC Classic HDA servers.
  • The OPC Classic HDA specifications are based on Microsoft's Object Linking and Embedding (OLE) and Distributed Component Object Model (DCOM) technologies. Therefore, OPC is endorsed by Microsoft.
  • You can configure DCOM client and server software programs to run on the same computer node or distributed across a network of computers.
  • The OPC Classic HDA is created to allow various automation applications to communicate with one another based on the historical data, regardless of the manufacturer. This allows greater flexibility and reliability when setting up automation systems.
  • The OPC Classic HDA server specification provides a common view of automation information managed by the system for which the server was written.
  • Developing OPC Classic-compliant applications is simplified because only one I/O interface is required.
  • Using OPC-compliant applications increases the flexibility of your automation processes because they can also communicate with devices other than those specified by the applications' developers.
  • Multiple OPC Classic HDA compliant client applications can communicate with an OPC Classic HDA server simultaneously.
For more information on OPC Classic HDA, visit the OPC Foundation's website.

Data Flow

The following diagram shows the data flow between the OPC Classic HDA clients, the OPC Classic HDA server, and Proficy Historian.