Operational overview

The OPC UA EDS adapter conforms to the OPC UA specification for operation. Once an instance of the adapter is defined in the system components configuration, it must be configured for it to create streams and collect data.

Adapter configuration

For an OPC UA EDS adapter instance to start data collection, configure the adapter by defining the following:

• Data source - Provide the connection information for the OPC UA data source.

• Data selection - Specify the OPC UA items to which the adapter instance should subscribe for data.

• Logging - Set up the logging behavior for the adapter instance.

For more information, see Data source configuration and Data selection configuration. For more information on how to configure logging, see Component-level logging configuration.

Connection

The OPC UA EDS adapter uses the binary opc.tcp protocol to communicate with the OPC UA servers. A secured connection is enabled by default where the X.509-type client and server certificates are exchanged and verified and the connection between the OPC UA EDS adapter and the configured OPC UA server is established.

Stream creation

The OPC UA EDS adapter creates types upon receiving the value update for a stream. One stream is created in Edge Data Store (EDS) for every selected OPC UA item in the data selection configuration.

Data collection

The OPC UA EDS adapter collects time-series data from selected OPC UA dynamic variables through OPC UA subscriptions (unsolicited reads). The adapter supports the Data Access (DA) part of OPC UA specification.

Stream properties

The OPC UA EDS adapter creates a stream with two properties per selected OPC UA item. The properties are described in the following table.

Stream ID is a unique identifier for each stream created by the adapter for a given OPC UA item. If the Custom Stream ID is specified for the OPC UA item in data selection configuration, the OPC UA EDS adapter uses that as a stream ID for the stream. Otherwise, the adapter constructs the stream ID using the following format constructed from the OPC UA item node ID:

<Adapter Component ID>.<Namespace>.<Identifier>

Note: The naming convention is affected by StreamIdPrefix and ApplyPrefixToStreamID settings in data source configuration. For more information, see Data source configuration.

Export operation

The OPC UA EDS adapter is able to export available OPC UA dynamic variables by browsing the OPC UA hierarchies or sub-hierarchies as part of the data source configuration process. For more information, see Data source configuration.

Buffering

Because the OPC UA EDS adapter sends data directly to EDS, buffering capability is not provided. EDS acts as a buffer before the data is egressed to either a PI Server or CONNECT data services. The amount of data stored in EDS is controlled by the following storage parameters:

• StreamStorageLimitMb

• StreamStorageTargetMb

For more information about configuring data storage in EDS, see Storage runtime configuration.