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OPC Toolbox

OPC Historical Data Access Client Object

You create an OPC Historical Data Access Client object to connect to an OPC HDA server. This client lets you browse the server namespace and retrieve fully qualified IDs of each item stored on the server. You use these IDs to request historical data from the server. You can retrieve raw or processed data stored on the OPC HDA server, specifying the IDs you want to retrieve, a time period for which to retrieve data, and optional parameters. OPC Toolbox supports the following read operations:

  • Retrieve raw data as it was stored on the server.
  • Retrieve data aggregated (processed) by the server. Each server implements different aggregate types, such as minimum, maximum, and average.
  • Retrieve data from specific time intervals. The server interpolates data from surrounding raw measurements.
  • Retrieve data that has been modified on the server. Some OPC HDA servers allow historical values to be modified, storing a history of values that have changed.

Data is retrieved into OPC HDA Data objects, which allow you to visualize and preprocess the historical data for further analysis in the MATLAB environment. Preprocessing operations include resampling, data conversion, and data display functions.

MATLAB code, used to connect to an OPC HDA server and access historical data for processing.

MATLAB code, used to connect to an OPC HDA server and access historical data for processing.

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