This function is used in Python Scripting.


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().

Client Permission Restrictions

This scripting function has no Client Permission restrictions.


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

Code Examples
Code 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