Good evening,

The title should have be named “Incorrect VariableTypes of Instantiated components of a custom BaseDataVariableType with a structured DataType”

I created an OPC UA data model using UaModeler, which contains a custom structure data type with 4 optional components. In UaModeler I selected to also automatically create a respective VariableType, containing the BaseDataVariable with the structure DataType and 4 (optional) BaseDataVariableType components, representing the individual structure elements.
Now another custom ObjectType definition contains the aforementioned automatically created Variable (mandatorily) and some other variables.

After generating code from the exported nodeset.xml, loading the nodesets and registering the models and instantiating the custom object, the server actually instantiates BaseVariableType instances for the underlying variables of the structured DataType variable instead of instances of BaseDataVariableType. As the generated code tries to cast the node to BaseDataVariableType, this cast fails and exceptions are thrown.

I tried to find out where those BaseVariabletype instances are created, but could not identify the spot.

Because the description above may be somewhat difficult to follow, here are the steps in short:

in UaModeler:

1. create custom structured dataType with 4 optional element
2. have UaModeler automatically create a variableTypeDefinition for the structured dataType
3. create custom ObjectType definition with mandatory variable component from step 2)
4. export nodesets.xml

in a custom ProsysSDK server:

1. load/register models
2. create instance of custom object
3. try to set value of the variable instance from step 2 above
   => com.prosysopc.ua.types.opcua.server.BaseVariableTypeNode cannot be cast to com.prosysopc.ua.types.opcua.server.BaseDataVariableTypeNode

The createInstance method actually creates BaseVariableType instances instead of BaseDataVariableType instances.
The generated nodesets have the correct types.

Another related question would be, why all 4 component variables have been created by the createInstance() method, despite the fact that all of them are optional, the values had not been set, and no custom configuration for the node creation had been setup. Shouldn’t only mandatory nodes be instantiated automatically?

SDK v4.6.0