The logical functionality of an AutomationComponent is represented by one or more FunctionalEntities described in 4.4. An important part of the functional model is the data exchange between FunctionalEntities using logical connections. Figure 8 illustrates this interaction.

A logical connection is represented by two ConnectionEndpoints, one on each FunctionalEntity that is part of the connection. Figure 28 provides a more detailed view of the Objects involved.

Logical connections are configured using ConnectionConfigurationSets.

The following types of logical connections are supported (see Figure 10):

Bidirectional connections describe bidirectional data exchange between two FunctionalEntities.

Unidirectional connections with heartbeat describe unidirectional data exchange in one direction and a heartbeat message (for logical connection monitoring) in the opposite direction between two FunctionalEntities.

Unidirectional connections describe unidirectional data exchange between two FunctionalEntities.

Autonomous publisher describes data published by a FunctionalEntity, where the related subscribing ConnectionEndpoint(s) are unknown to the logical connection.

Autonomous subscriber describes data subscribed by a FunctionalEntity, where the related publishing ConnectionEndpoint(s) are unknown to the logical connection.

Figure 10 – Connection types

Auditing reports problems and changes triggered by an external application. A subscription within a Connection is considered a source of data (for source of data, see OPC 10000-4). Changes in values of Variables from a data source do not generate Audit Events.