The M580 carries an embedded OPC UA server — so the level above (SCADA, EcoStruxure, a historian) can browse your variables by name and subscribe to them, no gateway in the middle. Browse the address space, watch a client subscription update live, and see why security is a connection precondition, not an afterthought.
On the left is the M580's OPC UA address space — click a node to see its NodeId, data type and live value. On the right, a client (think EcoStruxure or a SCADA) holds a subscription to three nodes and is pushed new values whenever they change. Drive the process, then change the security policy and watch the connection itself succeed or fail.
| Monitored item | Value | Source timestamp |
|---|
Set the policy to Basic256Sha256 with an untrusted client certificate and the session is refused with BadSecurityChecksFailed — the subscription never starts. That's the point: in OPC UA, trust between the server and client certificates is established before a single value flows. A subscription then beats polling — the server only sends a node when it actually changes (within the publishing interval), so a SCADA screen of 500 tags costs almost nothing on the wire.
🌳 Address space & NodeId. Everything is a node in a browsable tree — objects, variables, methods — each with a unique NodeId and a real data type. A client discovers your tags by browsing; no fixed register map to publish like Modbus.
🔔 Subscriptions & monitored items. Instead of polling, a client subscribes to the nodes it cares about with a publishing interval and a deadband. The server pushes changes — efficient, and you get a source timestamp and quality with every value.
🔐 Security built in. Mutual certificate trust, security policies (None → Basic256Sha256), message signing & encryption, and user tokens (anonymous / user+password). Security is negotiated at session setup — not bolted on.
☁️ Vendor-neutral to the edge. The same standard server feeds a Schneider SCADA, an EcoStruxure edge box, or anyone's historian. One protocol from the M580 up to the cloud — which is why OPC UA, not a proprietary link, is the IIoT default.
On the M580 you enable the server in Control Expert, choose which variables to expose (mark them in the data editor), set the endpoint and security policy, and load the certificates. From there it's standards all the way up — the upper level just browses and subscribes.
A SCADA needs 500 M580 tags on screen, most of them rarely changing. Why is an OPC UA subscription better than cyclically polling each one?