OPC-UA

This page describes how to configure a Tag that reads from or writes to an OPC-UA server.

Once the OPC-UA Data Connector is configured on an Area, all descendant Assets can use it when defining Tags.

OPC-UA data collection supports both On Change (subscription) and Periodic (polled) modes, and Tags can also be configured for Write operations.

Tag Configuration

The Tag must be configured such that the Data Connection uses a Data Connector that is of type OPC-UA. In the example below, the data connector is called OpcUaServer.

Tag configuration example for reading an OPC-UA value.

OPC-UA address format

Addressing in Opc-UA is identical whether it is reads or writes. In OPC UA, both read or write addresses are used to specify the location of data points within the OPC UA server. The correct format is: ns='namespace index';'identifier type'='identifier'

• ns (namespace index): Integer index of the namespace that defines the node. Namespaces are used to distinguish between different sets of node identifiers.

• identifier type and identifier: specifies the type of identifier used for the node.

  • i=<number> — Numeric identifier

  • s=<text> — String identifier

  • g=<guid> — GUID identifier

  • b=<base64> — Opaque (byte string) identifier

Examples

• ns=2;i=1234

• ns=3;s=TemperatureSensor1

• ns=4;g=550e8400-e29b-41d4-a716-446655440000

• ns=5;b=AAECAwQ=

If the server allows writing (to a node), use the exact same NodeId for writes.

Ensure the values you send or receive match the Tag data type.