SiOME

What you actually use it for

• Importing a companion specification nodeset and mapping its types onto PLC tags, so the controller serves a standard model.
• Building a server interface for a SIMATIC controller and exporting it for import into TIA Portal.
• Producing a companion-spec-conformant address space on a PLC without hand-writing NodeSet2 XML.
• Reviewing which mandatory nodes a companion specification requires and which PLC variable will supply each one, before any code is written.
• Authoring a small custom model where the controller is Siemens and the model will never leave that context.

Walkthrough

1. Get the PLC-side inputs firstYou need the tag or data-block structure that will back the model. Modelling before you know which variables exist and which are exposed by the controller's own configuration wastes the mapping work.
2. Import the base and companion nodesetsLoad Opc.Ua.Di.NodeSet2.xml and then the companion nodeset you are targeting, in dependency order. Note the model versions you imported and record them; a companion spec version change is the usual cause of a model that no longer matches a client.
3. Instantiate the companion typeCreate an instance of the machine type the specification defines, then work through its components. Mandatory nodes must all be satisfied; a client that validates instances against the ObjectType will skip an instance that is missing one.
4. Map each node to a PLC variableBind the model's variables to controller tags. This mapping is the deliverable, and it is where the semantic value is created: the same client code then works against this machine and against another vendor's machine implementing the same specification.
5. Export the server interface and import it in TIA PortalExport from SiOME and import into the TIA Portal project's OPC UA server interface configuration, then compile and download. What exactly is supported depends on the TIA Portal and firmware combination in front of you, so confirm before promising the model.
6. Re-read the NamespaceArray after the downloadA program download can change the server's namespace set. Read NamespaceArray again on the running controller and confirm that any client configuration references namespace URIs rather than indexes.
7. Verify with an independent clientConnect with UaExpert or opcua-commander and check HasTypeDefinition on the instance. If it does not resolve to the companion type you intended, the import did not do what you think it did.

What it will not do

• Windows only, and its value is concentrated in the Siemens toolchain; outside TIA Portal it is a plain nodeset editor.
• What you can actually deploy depends on the controller family, its firmware and, on many SIMATIC controllers, a runtime licence for the OPC UA server. The editor will happily let you model something the target cannot serve.
• It does not validate against a live server. Conformance to the companion specification is only proven by browsing the running controller.
• Companion specification version churn is not handled for you; re-importing a newer nodeset can invalidate mappings.
• It is a modelling and mapping tool, not a diagnostic or performance tool.

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.