3 Terms, definitions and conventions

3.1 Overview

It is assumed that basic concepts of OPC UA information modelling and PROFINET are understood in this specification. This specification will use these concepts to describe the PROFINET OPC UA Information Model. For the purposes of this document, the terms and definitions given in [OPC 10000-1], [OPC 10000-3], [OPC 10000-4], [OPC 10000-5], [OPC 10000-7], [OPC 10000-100], as well as the following apply.

3.2 OPC UA for PROFINET terms

3.2.1 Asset

A piece of hardware and/or software which has a value for the user. In the scope of this document assets can discover properties like vendor, version or installation information by means of defined PROFINET services.

3.2.2 Startup Parameters

Device specific parameters which are set by the end user in the engineering system of the PLC. The parameter layout is described in the GSD file of the device. The configured values are transferred to the device during startup.

3.2.3 Tag-Function

The portion of the application specific device identification which defines the application specific function of an asset. The Tag Function is given during the planning phase of a plant e.g. by ECAD engineering tools. The specific usage of Tag-Function is defined by the OEM.

3.2.4 Tag-Location

The portion of the application specific device identification which defines the application specific location of an asset. Usually the TAG-Location is unique inside of a whole plant or OEM company. The Tag-Location is given during the planning phase of a plant e.g. by ECAD engineering tools. The specific usage of Tag-Location is defined by the OEM.

3.2.5 Edge Gateway

A physical device with one interface to the cell and an OPC UA interface to the factory.

3.3 Abbreviations and symbols

3.4 Conventions used in this document

3.4.1 Conventions for Node descriptions

Node definitions are specified using tables (see Table 2).

Attributes are defined by providing the Attribute name and a value, or a description of the value.

References are defined by providing the ReferenceType name, the BrowseName of the TargetNode and its NodeClass.

• If the TargetNode is a component of the Node being defined in the table, the Attributes of the composed Node are defined in the same row of the table.

• The DataType is only specified for Variables; “[<number>]” indicates a single-dimensional array, for multi-dimensional arrays the expression is repeated for each dimension (e.g. [2][3] for a two-dimensional array). For all arrays the ArrayDimensions is set as identified by <number> values. If no <number> is set, the corresponding dimension is set to 0, indicating an unknown size. If no number is provided at all the ArrayDimensions can be omitted. If no brackets are provided, it identifies a scalar DataType and the ValueRank is set to the corresponding value (see [OPC 10000-5]. In addition, ArrayDimensions is set to null or is omitted. If it can be Any or ScalarOrOneDimension, the value is put into “{<value>}”, so either “{Any}” or “{ScalarOrOneDimension}” and the ValueRank is set to the corresponding value (see [OPC 10000-3]) and the ArrayDimensions is set to null or is omitted. Examples are given in Table 1.

• The TypeDefinition is specified for Objects and Variables.

• The TypeDefinition column specifies a symbolic name for a NodeId, i.e. the specified Node points with a HasTypeDefinition Reference to the corresponding Node.

• The ModellingRule of the referenced component is provided by specifying the symbolic name of the rule in the ModellingRule column. In the AddressSpace, the Node shall use a HasModellingRule Reference to point to the corresponding ModellingRule Object.

If the NodeId of a DataType is provided, the symbolic name of the Node representing the DataType shall be used.

Nodes of all other NodeClasses cannot be defined in the same table; therefore only the used ReferenceType, their NodeClass and their BrowseName are specified. A reference to another part of this document points to their definition.

Table 2 illustrates the table. If no components are provided, the DataType, TypeDefinition and ModellingRule columns may be omitted and only a Comment column is introduced to point to the Node definition.

Components of Nodes can be complex that is containing components by themselves. The TypeDefinition, NodeClass, DataType and ModellingRule can be derived from the type definitions, and the symbolic name can be created as defined in 3.4.3.1. Therefore, those containing components are not explicitly specified; they are implicitly specified by the type definitions.

3.4.2 NodeIds and BrowseNames

3.4.2.1 NodeIds

The NodeIds of all Nodes described in this standard are only symbolic names. Annex A defines the actual NodeIds.

The symbolic name of each Node defined in this specification is its BrowseName, or, when it is part of another Node, the BrowseName of the other Node, a “.”, and the BrowseName of itself. In this case “part of” means that the whole has a HasProperty or HasComponent Reference to its part. Since all Nodes not being part of another Node have a unique name in this specification, the symbolic name is unique.

The namespace for all NodeIds defined in this specification is defined in Annex A. The NamespaceIndex for this namespace is Server-specific and depends on the position of the namespace URI in the server namespace table.

Note that this specification not only defines concrete Nodes, but also requires that some Nodes shall be generated, for example one for each Session running on the Server. The NodeIds of those Nodes are Server-specific, including the namespace. But the NamespaceIndex of those Nodes cannot be the NamespaceIndex used for the Nodes defined in this specification, because they are not defined by this specification but generated by the Server.

3.4.2.2 BrowseNames

The text part of the BrowseNames for all Nodes defined in this specification is specified in the tables defining the Nodes. The NamespaceIndex for all BrowseNames defined in this specification is defined in Annex A.

If the BrowseName is not defined by this specification, a namespace index prefix like ‘0:EngineeringUnits’ or ‘2:DeviceRevision’ is added to the BrowseName. This is typically necessary if a Property of another specification is overwritten or used in the OPC UA types defined in this specification. Table 110 provides a list of namespaces and their indexes as used in this specification.

3.4.3 Common Attributes

3.4.3.1 General

The Attributes of Nodes, their DataTypes and descriptions are defined in [OPC 10000-3]. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attribute value is defined by this specification or if it is server specific.

For all Nodes specified in this specification, the Attributes named in Table 3 shall be set as specified in the table.

3.4.3.2 Objects

For all Objects specified in this specification, the Attributes named in Table 4 shall be set as specified in the Table 4. The definitions for the Attributes can be found in [OPC 10000-5].

3.4.3.3 Variables

For all Variables specified in this specification, the Attributes named in Table 5 shall be set as specified in the table. The definitions for the Attributes can be found in [OPC 10000-5].

3.4.3.4 VariableTypes

For all VariableTypes specified in this specification, the Attributes named in Table 6 shall be set as specified in the table. The definitions for the Attributes can be found in [OPC 10000-5].

3.4.3.5 Methods

For all Methods specified in this specification, the Attributes named in Table 7 shall be set as specified in the table. The definitions for the Attributes can be found in [OPC 10000-5].