UaExpert

What you actually use it for

• Proving a server is reachable and its endpoints usable before you write a line of client code.
• Walking an unfamiliar address space and checking HasTypeDefinition to see whether a companion specification is genuinely implemented or only named in a datasheet.
• Building a Data Access view of candidate tags and watching value, StatusCode, SourceTimestamp and ServerTimestamp update live.
• Reading history and testing server-side aggregates through the historical-access plugin before you commit to pulling raw data.
• Subscribing to alarms and conditions to confirm what a server actually emits and how it behaves on ConditionRefresh.
• Triggering the certificate exchange that seeds a server's trust list, so the rejected-to-trusted workflow is done once by hand before automation touches it.

Walkthrough

1. Add the server by endpoint URLIn the Project pane, right-click Servers and choose Add. Under Custom Discovery, double-click the placeholder row and paste a full endpoint URL, for example opc.tcp://opcua.umati.app:4840. UaExpert calls GetEndpoints and lists every EndpointDescription the server advertises.
2. Start with security None to separate network faults from PKI faultsPick the None / None endpoint first. If that connects, the network path, port and endpoint path are fine and anything that fails next is certificates, policy or authentication. If it does not connect, stop and test TCP reachability instead.
3. Add the same server again on a signed and encrypted endpointSelect a Basic256Sha256 endpoint with SignAndEncrypt. The first attempt normally fails with BadCertificateUntrusted. UaExpert offers to trust the server certificate; accept it, then go to the server side and move UaExpert's own certificate from its rejected store to its trusted store. Both directions must be done.
4. Inspect UaExpert's own certificate storesSettings then Manage Certificates shows UaExpert's application instance certificate, its trusted and issuer lists and its rejected folder. This is where you check that the certificate's ApplicationUri matches the URI entry in its Subject Alternative Name if the server rejects it with a URI error.
5. Browse, then read the Attribute and Reference panesExpand Root then Objects. Selecting a node fills the Attribute pane with NodeId, NodeClass, DataType, ValueRank, ArrayDimensions and AccessLevel, and the Reference pane with HasTypeDefinition, HasComponent and HasProperty. The type definition is the fastest honest answer to whether a machine is modelled or just tag-dumped.
6. Drag nodes into a Data Access view and tune the monitored itemsDrop nodes onto a Data Access document to create monitored items. Right-click a row to set sampling interval, queue size and a deadband filter, and watch whether the server accepts your request or silently revises it. The revised values are what the server will actually deliver.
7. Add the plugin document for the jobDocument then Add opens the document-type picker: history trend, event view, performance test and PubSub configuration among them. Which plugins are present depends on your installed build, so check the picker rather than assuming.
8. Save the projectSaving keeps the endpoint, chosen security, certificate decisions and views together, so the next engineer reproduces your session instead of rediscovering it.

What it will not do

• Windows only. There is no native Linux or macOS build, so it cannot be used for headless diagnostics on a gateway you only reach over SSH.
• It is a client and a test tool, not a server, gateway or historian. It does not persist collected data in a form you can build on.
• Everything is manual GUI work. There is no scripting surface, so it cannot be wired into a CI job or a nightly regression test against a fleet.
• Plugin availability varies by build and licence tier, and the wider Unified Automation product line (UaModeler, UaGateway, the SDKs) is separately licensed.
• Its PubSub support is a plugin and lags the specification; do not assume it covers your transport or security key service arrangement.

Alternatives

Last verified 7 September 2026 against OPC UA 1.05.07. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.