OPCUA and extension object tag

I should to communicate with a Beckhoff PLC via OPC UA
also I need read some ‘extension objects’ exposed from OPC UA. Ignition support this complex data?

In attachment few pictures of OPC UA Expert Client where you can see the data that I need read


Maybe is there a syntax where I can read single elements of the extension objects?

Thank you very much
Best regards


It’s not possible to read structures in the current version of the OPC UA module.

We have ongoing work to support this but it won’t be publicly available until Ignition 8.

Hi Kevin

Thank you very much


Hi Kevin.
Is there an update of the status on the extension object support development via OPC-UA in the OPC UA module of ignition?

I really need this feature

Regards Niels

If you’re willing to use a transitionary beta module (referred to as “OPC UA Next” around the forums) I can get you a copy of it.

That would be perfect. Please provide a copy for me.

While we are at it. I see some discussion on OPC-UA method calls. Is that also included in the current OPC UA Next development or would I need to wait for the version 8 release?

Did this ever get integrated into the base OPC UA package for Ignition?

Yes, since sometime in the 7.9 series Ignition can read custom structures. The only caveat is that the server must support the OPC UA 1.03 and prior DataType Dictionary mechanism. Ignition does not yet support the new DataTypeDefinition attribute introduced in OPC UA 1.04.

I'm not sure now if I'm even trying to do the same thing as this original topic. We're trying to use the system.opcua.callMethod function, and we apparently need to pass in an ExtensionObject as a parameter to the function.

The code below on GitHub shows how to use Python to call the method, but it is using asyncua.ua.uatypes.ExtensionObject (e.g. line 37 & 38). I'm basically trying to find something similar in Ignition to put the data in the format that is required by the device when we call the method via Ignition.

Yeah, it's a little off topic, but basically you have to build a JSON object that mirrors the structure and try to pass it as an input: OPC-UA - Method call with "complex" input values

It may or may not work depending on your Ignition version and whether the server supports the DataType Dictionary or not. Are there any structured values in the server you can try to read or subscribe to and find out?

That topic looks helpful. Thank you!!