Figure 2depicts the main ObjectTypesof the Sercosdevice model and their relationships. The drawing is not intended to be complete. For simplicity only a few components and relations were captured so as to give an overview of the overall structure.

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Figure 2– Device Model Overview

The symbols in this drawing are according to the OPC UA symbol elements. Figure 2shows the ObjectTypesused in this specification as well as some elements from other specifications that help understand some modelling decisions. The upper grey box shows the OPC UA base information model from which the TopologyElementTypeand ProtocolType are derived. The grey box in the second level shows the main ObjectTypesfrom the OPC UA for Devices Companion Specification. The grey box in third level shows the Sercos OPC UA information model that this specification introduces. The components of those ObjectTypesare illustrated only in an abstract way in this overall figure. The grey box in the fourth level shows an example of a basic drive model.

TopologyElementTypeis the base ObjectTypefor elements in a device topology. It introduces Parameters(ParameterSet) and Methods(not shown). This specification also defines a functional grouping concept to provide alternative viewpoints.

A class of devices is represented by the DeviceType ObjectType. This includes predefined elements to describe and identify a device. SercosDeviceTypeextends the DeviceType. Therefore the elements are inherited fromFunctionalGroupType, TopologyElementTypeand DeviceType. All OPC UA mandatory elements are implemented.

SercosProtocolTyperepresents the Sercos communication protocol implemented by the TopologyElement.