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04/17/2015
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Hi,
I just downloaded the newest version of the specifications and I had already read the previous version (in parts). I have a question about the differences in Part 11- Historical Access between the two versions of the specifications. The HistoricalDataNode is clearly defined as Variables or Properties in the older specifications, whereas its quite confusing in the new version of the specifications. All I would like to know is that if the specifications allows normal Objects (e.g Instance of a User Defined UA Type) to be a HistoricalDataNode or not? It is clear that normal Objects can be a HistoricalEventNode but the newer version creates a quite a bit of confusion about HistoricalDataNode.
It would be great if someone at the OPC Foundation could clarify my query.
Regards,
Suprateek
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02/24/2014
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Suprateek,
I think the definition (show below) is fairly clear.
3.1.4 HistoricalDataNode - Variable or Property in the AddressSpace where a Client can access historical data
Objects do not have a Value associated with them so they are not HistoricalDataNodes, they can be HistoricalEventNodes (since they do support events). Not all variables or properties include history, but all are allowed to have history. What part of the specification made it unclear?
Paul
Paul Hunkar - DSInteroperability
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