While device data and methods related to the device are defined in separate areas of the OPC UA Information model (i.e. ParameterSet and MethodSet), they are organized by functional groups into a concise representation, which may be structured to present different aspects of the device. A DTM provides different interfaces (e.g. IDeviceData and IFunction), where data and methods are presented independently, while each interface may provide an own structure.
In the mapping from DTM interfaces to OPC UA information model, the representation hierarchies of IData interfaces and IFunction interface are combined into FunctionalGroups to provide a concise representation of the device data and methods within one hierarchy.
This means, that the data of the IData interfaces are mapped to the ParameterSet node in the OPC UA Information model and the command functions from IFunction interface are mapped to the MethodSet of the device. The hierarchical structures in the IData and IFunction interfaces are mapped to the hierarchical structure provided by the FdtFunctionalGroup elements, which organize the representation of data and methods (see Figure 14).
Figure 14 – Example for mapping of data and function information