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11:38, EEST
June 25, 2014
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Hello,
I would like to ask about network performance and differences of methods UaClient.readAttribute and UaClient.readValues.
My situation is following:
Application is located in a destination with a long distance from OPC server (ping between servers is around 150ms) and I do 10-20 synchronous reads of nodes like UA.readAttribute(nodeId, Attributes.Value). Every read takes around 200 – 300 ms, that’s from 2 to 6 seconds in total.
My question is when I use UaClient.readValues(nodeIds[], …), where nodeIds is an array of all these 10-20 nodes whether internally this is translated to one “big” read from OPC server or is it just a series of reads similar to sequence of single reads. Or is there another better way how to read bigger amount of nodes?
I tried to analyze network traffic, but I wasn’t able to see the difference.
Thank you,
Ladislav Asenbrener
15:05, EEST
December 21, 2011
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Yes, readValues() combines the read to a single read() call.
Note: if the server defines OperationLimits, those limits are obeyed to break the actual read call to smaller chunks, but it should not affect calls of 10-20 items in practice.
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