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Reads processed values from the OPC-HDA server. Processed values are calculated values, based on the aggregate function requested for each item. The list of aggregates can be obtained by calling system.opchda.getAggregates().

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system.opchda.readProcessed(serverName, itemIds, startDate, endDate, resampleIntervalMS, aggregates)

  • Parameters

String serverName - The name of the defined OPC-HDA server to read.

List[String] itemIds - A list of item ids to read.

Any startDate - The starting date/time of the query.

Any endDate - The ending date/time of the query.

Integer resampleIntervalMS - The interval, in milliseconds, that each value should cover.

List[Integer] aggregates - A list which should be one-to-one with the item ids requested, specifying the integer id of the aggregation function to use. The aggregation ids are defined in the OPC-HDA specification. The list of aggregates can also be obtained by calling system.opchda.getAggregates().

  • Returns

List[ReadResults] - A list of read results which is one-to-one with the item IDs passed in. The ReadResult object has a 'serviceResult' quality property that indicates whether the call was successful, and is itself a list of QualifiedValues.

  • Scope

Gateway, Vision Client, Perspective Session

titleCode Examples
Code Block
titleCode Snippet
# This example will read processed data from a Matrikon server between two specified dates.
# Declare start and end dates
start =, 3, 14)
end =

# Call system function and print results
readValue = system.opchda.readProcessed("Matrikon",[1],start,end,1000,[1])
print readValue

system opchda readProcessed, opchda.readProcessed