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OPC UA Browsing issues

24 May 2020 08:03 #8507 by support
Replied by support on topic OPC UA Browsing issues
The additional information you are looking for is not available directly through browsing, but you need to read it from the server, for any node you are interested in.

Most of is you can get by simply reading from the node you have browsed into, but instead of reading the default Value attribute, you need to specify a different attribute. Refer to UA specs for details. Here is a list of all attributes: .

Of particular interest to you are: ArrayDimensions, DataType, Description, NodeClass, ValueRank.

Related examples:

You will find the NodeIds for the built-in data types in UA specs. We have UADataTypeIds class with NodeIds of all data types, including built-in types, so you can use that when comparing/dissecting the data types : .

Some information you mentioned (Engineering Units) is more complicated to get to. It might be implemented as OPC UA Properties, which are additional nodes you need to browse into, and then read their values.

Best regards

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23 May 2020 18:20 #8505 by KarimgSaikali
As a first stage, we only want to access UA server considering there are no security policies and no need for user authentication and certificates.

- All good for browsing and selection of UA server.

- For browsing as a first stage, we only want to Browse Nodes and simple data Leaf (simple means native datatype like int32, bool, float, string, etc.. not complex datatype structure).

In OPC DA, when iterating over the DANodeElementCollection, the DANodeElement has .IsLeaf or .IsItem property that allows us to determine that a node is a data leaf.

it seems that with OPC UA there is much more complexity in the data browsed.

- The UANodeElement has not the .IsLeaf and .IsItem property to determine if a node is a simple (native) datatype.

We are aware that there is the EasyUAClient.BrowseDataVariables() method, but we need to filter the results only for simple datatype as mentioned above,

and excluded data structure from the results. How to achieve this?

- Suppose we achieve above and we get the UANodeElementCollection as the result of all simple type data leaves under a specific node,

how to retrieve for each UANodeElement, its NodeId, datatype (int32, float, bool, etc..) , IsArray, ArraySize, EU limits, EU unit & description?

Looking forward to your prompt answer

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