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02/12/2016
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Hello,
With reference to Part 13: Aggregates OPC UA Specifications I have the following questions
- Use Bounds criteria has the 3 options (None, Simple , Interpolated) and Simple bounding is introduced in this latest version of OPC UA specifications.
- The aggregate characteristics specified in the sections from 5.4.3.5 to 5.4.3.40 (Table 16 to Table 50) are standard for the corresponding aggregate?
- Do we have flexibility to change the characteristics for any specific aggregate?
Example :Can we specify UseBounds as Interpolated instead of Simple for Mimimum2 aggregate?
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02/24/2014
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No. Aggregates are defined to have exact behavior. You can define your own custom aggregates, if you would like different behavior. The OPC Foundation aggregates have the behavior defined in the specification.
Paul Hunkar - DSInteroperability
04/01/2014
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Just to be clear Paul’s answer is “No. Aggregates are …”. The period there is important. 
Rod Stein Manager of Technology Matrikon OPC http://www.matrikonopc.com
02/12/2016
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Hello,
Sorry to ask the same question again.
The OPC UA specification describes that Minimum2 aggregate uses Simple Bounding technique.In this context
Can we specify UseBounds as Interpolated instead of Simple ?
As I understand from the OPC UA document, Simple bounding technique is introduced in the latest version only.
What was the recommended bounding technique for Minimum2 and other similar aggregates in the previous editions?
BTW, The below statement (first response) is very much confusing.
No. Aggregates are defined to have exact behavior. You can define your own custom aggregates, if you would like different behavior. The OPC Foundation aggregates have the behavior defined in the specification.
04/01/2014
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I will try to clarify the response for you. The aggregates as they are defined in UA part 13 are not allowed to be changed. If you want to implement the Minimum aggregate in an OPC UA server then you must follow what is defined in Part 13. If you want an aggregate that is very similar to Minimum but isn’t the same as Minimum you are allowed to create your own custom aggregate but you cannot call it by an existing pre-defined aggregate name. In this case you could not call it Minimum but could call it MinimumEx. If you want to create an aggregate similar to Minimum2 but uses Interpolated bounds then create a custom aggregate and call it something unique so that no one confuses it with the Minimum2 aggregate as defined in part 13.
The aggregate definitions from classic OPC HDA specification were the same as the non-numbered version of the aggregate. So Minimum was the same as in Classic OPC and Minimum2 is new for UA. Not all non-numbered aggregates existed in the Classic OPC specifications.
I hope this clarifies it for you.
Rod Stein Manager of Technology Matrikon OPC http://www.matrikonopc.com
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