This ObjectTypeis a subtype of ServerRedundancyTypeand is used to identify the capabilities of the OPC UA Serverfor server-controlled redundancy with a transparent switchover for the client. It is formally defined in Table 16.

Table 16– TransparentRedundancyType Definition

Attribute

Value

BrowseName

TransparentRedundancyType

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the ServerRedundancyType defined in 6.3.7, i.e. inheriting the InstanceDeclarations of that Node.

HasProperty

Variable

CurrentServerId

String

PropertyType

Mandatory

HasProperty

Variable

RedundantServerArray

RedundantServerDataType[]

PropertyType

Mandatory

RedundancySupportis inherited from the ServerRedundancyType. It shall be set to TRANSPARENT_4 for all instances of the TransparentRedundancyType.

Although, in a transparent switchover scenario, all redundant Serversserve under the same URI to the Client, it may be required to track the exact data source on the Client. Therefore, CurrentServerId contains an identifier of the currently-used Serverin the Redundant Set. This Serveris valid only inside a Session; if a Clientopens several Sessions, different Serversof the redundant set of Serversmay serve it in different Sessions. The value of the CurrentServerIdmay change due to Failoveror load balancing, so a Clientthat needs to track its data source shall subscribe to this Variable.

As diagnostic information, the RedundantServerArraycontains an array of available Serversin the Redundant Set; including their service levels (see 12.7). This array may change during a Session.