OPCUA and extension object tag

andrea.minu · February 9, 2018, 2:13pm

Hello
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

Andrea

Kevin.Herron · February 9, 2018, 3:25pm

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.

andrea.minu · February 9, 2018, 3:51pm

Hi Kevin

Thank you very much

Andrea

ncj · September 7, 2018, 1:01pm

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

Kevin.Herron · September 7, 2018, 3:10pm

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.

ncj · September 8, 2018, 9:16am

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?

rbachman · March 3, 2023, 5:39pm

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

Kevin.Herron · March 3, 2023, 5:41pm

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.

rbachman · March 3, 2023, 6:12pm

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.

github.com

heidepriem/RFU6xxPythonExample/blob/main/RFU6xxClient.py

'''
Created on 29.11.2021

@author: Sebastian Heidepriem (SICK AG)
'''
from asyncua.client.client import Client
from asyncua.common.node import Node
from asyncua.ua.uatypes import ExtensionObject, ByteString, Int32
from asyncua.common.node import ua
import struct
import string

class RFU6xxClient(object):
    
    client : Client = None
    nsAutoID : int = 0
    nsOpcDI : int = 0
    nsRfu : int = 0
    
    rfu6xxNode : Node = None

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Kevin.Herron · March 3, 2023, 6:14pm

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?

rbachman · March 3, 2023, 6:22pm

That topic looks helpful. Thank you!!