OPC UA adapter

The OPC UA adapter connects to an OPC UA server with a read-only session and reads configured node ids on a poll interval, publishing each one onto the Unified Namespace.

Read-only by construction

The adapter never opens a session capable of writing a node value — see Security model for how this fits the broader isolation design, and OT network safety for where this adapter sits relative to the plant’s control network.

Configuring a device

A device entry names the server connection and a list of tags, each mapping a node id to a signal path:

devices:
  - id: cnc-2-opcua
    protocol: opcua
    poll_ms: 200
    conn: {kind: opcua, host: <server-host>, port: 4840}
    tags:
      - {node_id: "ns=2;s=SpindleLoad", signal_path: "press-shop/line-1/cnc-cell-2/cnc-2/cnc-2-spindle-load"}

The namespace index (ns=) and identifier format must match your server’s address space — check your OPC UA server’s own node browser or documentation for the exact ids it exposes. signal_path must match a signal id already present in the site’s registry (see Sensors & recipes).

Trying it against the simulator

The demo plant’s rw-sim runs an OPC UA server with fixed, documented node ids, and deploy/demo/edge.yaml is a complete, working example device entry for it — see Quick start to bring the whole chain up and watch samples land in the historian.