Clause 5introduces References, the ProtocolType, and basic TopologyElementTypesneeded to create a communication topology. The types for this model are illustrated in Figure 16.

Figure 16– Device communication model overview

A ProtocolType ObjectTyperepresents a specific communicationprotocol (e.g., FieldBus) implemented by a certain TopologyElement. Examples are shown in Figure 18.

The ConnectionPointTyperepresents the logical interface of a Deviceto a Network.

A Networkis the logical representation of wired and wireless technologies.

Figure 17provides an overall example.

Figure 17– Example of a communication topology

The ProtocolType ObjectTypeand its subtypes are used to specify a specific communication (e.g., FieldBus) protocol that is supported by a Device(respectively by its ConnectionPoint) or Network. The BrowseNameof each instance of a ProtocolType shall define the Communication Profile(see Figure 18).

Figure 18shows the ProtocolTypeincluding some specific types and instances that represent Communication Profilesof that type. It is formally defined in Table 39.

Figure 18– Example of aProtocolType hierarchy with instancesthat represent specific communication profiles

Table 39– ProtocolType definition

Attribute	Value
BrowseName	ProtocolType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:BaseObjectType defined in OPC 10000-5
Conformance Units
DI Network
DI Protocol

A Networkis the logical representation of wired and wireless technologies and represents the communication means for Devicesthat are connected to it. A Networkinstance is qualified by its Communication Profilecomponents.

Figure 19shows the type hierarchy and the NetworkTypecomponents. It is formally defined in Table 40.

Figure 19– NetworkType

Table 40– NetworkType definition

Attribute	Value
BrowseName	NetworkType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:BaseObjectType defined in OPC 10000-5.
0:HasComponent	Object	<ProfileIdentifier>		ProtocolType	MP
ConnectsTo	Object	<CPIdentifier>		ConnectionPointType	OP
0:HasComponent	Object	Lock		LockingServicesType	O
Conformance Units
DI Network

The <ProfileIdentifier> specifies the Protocoland Communication Profilethat this Networkis used for.

<CPIdentifier> (referenced by a ConnectsTo Reference) references the ConnectionPoint(s) that have been configured for this Network. All ConnectionPoints shall adhere to the same Protocolas the Network. See also Figure 22for a usage example. They represent the protocol-specific access points for the connected Devices.

In addition, Networksmay also support LockingServices(defined in 7).

Clientsshall use the LockingServicesif they need to make a set of changes (for example, several Writeoperations and Methodinvocations) and where a consistent state is available only after all of these changes have been performed. The main purpose of locking a Networkis avoiding concurrent topology changes.

The lock on a Networkapplies to the Network, all connected TopologyElementsand their components. If any of the connected TopologyElementsprovides access to a sub-ordinate Network(like a gateway), the sub-ordinate Networkand its connected TopologyElementsare locked as well.

If InitLockis requested for a Network, it will be rejected if any of the Devicesconnected to this Networkor any sub-ordinate Networkincluding their connected Devicesis already locked.

If the Online/Offline model is supported (see 6.3), the lock always applies to both the online and the offline version.

This ObjectTyperepresents the logical interface of a Deviceto a Network. A specific subtype shall be defined for each protocol. Figure 20shows the ConnectionPointTypeincluding some specific types.

Figure 20– Example of ConnectionPointType hierarchy

A Devicecan have more than one such interface to the same or to different Networks. Different interfaces usually exist for different protocols. Figure 21shows the ConnectionPointTypecomponents. It is formally defined in Table 41.

Figure 21– ConnectionPointType

Table 41– ConnectionPointType definition

Attribute	Value
BrowseName	ConnectionPointType
IsAbstract	True
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the TopologyElementType defined in 4.2.
0:HasComponent	Object	NetworkAddress		FunctionalGroupType	M
0:HasComponent	Object	<ProfileIdentifier>		ProtocolType	MP
ConnectsTo	Object	<NetworkIdentifier>		NetworkType	OP
Conformance Units
DI ConnectionPoint

ConnectionPointsare components of a Device, represented by a subtype of ComponentType. To allow navigation from a Networkto the connected Devices, the ConnectionPointsshall have the inverse Reference (ComponentOf)to the Device.

ConnectionPointshave Propertiesand other components that they inherit from the TopologyElementType.

The NetworkAddress FunctionalGroupincludes all Parametersneeded to specify the protocol-specific address information of the connected Device. These Parametersmay be components of the NetworkAddress FunctionalGroup, of the ParameterSet, or another Object.

<ProfileIdentifier> identifies the Communication Profilethat this ConnectionPointsupports. ProtocolTypeand Communication Profileare defined in 5.2. It implies that this ConnectionPointcan be used to connect Networksand Devicesof the same Communication Profile.

ConnectionPointsare between a Networkand a Device. The location in the topology is configured by means of the ConnectsTo ReferenceType. Figure 22illustrates some usage models.

Figure 22– ConnectionPoint usage

The ConnectsTo ReferenceTypeis a concrete ReferenceTypeused to indicate that source and target Node have a topological connection. It is both hierarchical and symmetric, because this is natural for this Reference. The ConnectsTo Referenceexists between a Networkand the connected Devices(or their ConnectionPoint, respectively). Browsing a Networkreturns the connected Devices; browsing from a Device, one can follow the ConnectsTo Referencefrom the Device’s ConnectionPointto the Network.

The ConnectsToParent ReferenceTypeis a concrete ReferenceTypeused to define the parent (i.e. the communication Device) of a Network. It is a subtype of The ConnectsTo ReferenceType.

The two ReferenceTypesare illustrated in Figure 23.

Figure 23– Type Hierarchy for ConnectsTo and ConnectsToParent References

The representation in the AddressSpaceis specified in Table 42and Table 43.

Table 42– ConnectsTo ReferenceType

Attributes	Value
BrowseName	ConnectsTo
Symmetric	True
IsAbstract	False
References	NodeClass	BrowseName	Comment
Subtype of 0:HierarchicalReferences ReferenceType defined in OPC 10000-5.
Conformance Units
DI ConnectsTo

Table 43– ConnectsToParent ReferenceType

Attributes	Value
BrowseName	ConnectsToParent
Symmetric	True
IsAbstract	False
References	NodeClass	BrowseName	Comment
Subtype of ConnectsTo ReferenceType
Conformance Units
DI ConnectsTo

Figure 24illustrates how this Referencecan be used to express topological relationships and parental relationships. In this example two Devicesare connected; the module DPcomm is the communication Devicefor the Network.

Figure 24– Example with ConnectsTo and ConnectsToParent References

All Networksshall be components of the NetworkSet Object.

The NetworkSet Nodeis formally defined in Table 44.

Table 44– NetworkSet definition

Attribute	Value
BrowseName	NetworkSet
References	NodeClass	BrowseName	TypeDefinition
OrganizedBy by the 0:Objects Folder defined in OPC 10000-5
0:HasTypeDefinition	ObjectType	0:BaseObjectType
Conformance Units
DI NetworkSet