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Property node in another namespace than its parent
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Jonas Green
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05/12/2021 - 06:45
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Hi,

Is it allowed to model a property node of an object node in another namespace than the object node is modelled in?

E.g. I have an object node in namespace index #3. The object type (modelled in namespace index #2) of this object defines a mandatory property. I modell the property variable node is modelled in namespace index #4. The object node references the property variable node with an HasProperty reference. Does it somehow violates the specification to put the property node in another namespace?

 

Best regards,

Jonas.

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Randy Armstrong
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05/12/2021 - 08:13
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Yes. Property Names on types can come from other information models that define well known properties.

An example is the Icon property that can be added to any ObjectType:

https://reference.opcfoundatio.....rt3/5.8.3/

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Jonas Green
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05/17/2021 - 02:36
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Ok, it is possible to model object types with properties from other information models. But is it possible to model an instance of an object type (that defines properties) where the object instance is in one namespace while the properties of the object instance is in another namespace?

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Randy Armstrong
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05/17/2021 - 07:38
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That is what you get when you use interfaces:

https://reference.opcfoundatio.....mendment7/

If you don't have an interface or another reference to another information model then question becomes why?

It adds complexity for no real benefit.

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Jonas Green
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05/18/2021 - 02:08
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My use case is to "tagg" certain variable nodes of my information model by modelling them in a specific namespace to internally map those variables nodes to internal parameters of a sub-system in my application. When variable nodes of that namespace is requested my application will load corresponding parameter from the sub-system and translate it to an OPC UA variable.

By using a namespace I can tagg certain OPC UA variables to be mapped with a standard information model mechanism (namespaces), I can filter out node requests internally based on the namespaceIndex portion of the NodeId and I get a complete numeric NodeId range that can map to 1:1 to internl parameters of the sub-system.

I just want to make sure that I don't violate any OPC UA requirement by doing so.

 

Thanks,

Jonas.

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Randy Armstrong
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05/18/2021 - 05:03
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I just want to make sure that I don't violate any OPC UA requirement by doing so.

Nope. You are good.

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