Hot to call a method with argument array as input

[uioplmn]

Hi. I am new to OPC UA and stuck with calling a method with an argument array as input. I posted the details of my question on Stack Overflow.

Can anybody give me a hint? Thanks!

[AndreasHeine]

you should not pass a list of values instead you should pass a list of ua.Variant classes with the right types of each like shown in the method input arguments (e.g. UaExpert)

[h0tnanny]

Hey! I had a similar problem, but the solution presented above did not help

[AndreasHeine]

because your inputargument is an extensionobject (ScanSettings)!

[h0tnanny]

Thanks, can you please tell me how to correctly pass the input parameters?

[AndreasHeine]

your client need to load the typedefinitions and then create a instance of that definition/class and pass it as value! but this library is deprecated not sure if it works you should switch to asyncua.

[h0tnanny]

Thank you very much, I will try!

[KolbenKeule]

Hi, I have a big problem with VariantType.ExtensionObject and install asyncua but I don´t know how it´s work. Sry I´m new with OPC-UA too :( I search for some weeks for a solution but nothing works.

[AndreasHeine]

@KolbenKeule

The library is deprecated.
Please switch to : opcua-asyncio which also has a sync-wrapper, with very few changes in API**

[KolbenKeule]

Hi, thank you for the fast answer.
I got opcua-asyncio running and found a good example for calling a method. But I get struggel with the nodes. I have no idea how can fix the problems and run the code.


Can you help me again please?

[AndreasHeine]

i pinged you yesterday from FreeOpcUa/opcua-asyncio#839 on how to use ExtensionObjects!

[KolbenKeule]

Thank you very much. I only have a problem to understand this completely :(

[AndreasHeine]

https://reference.opcfoundation.org/v104/Core/docs/Part6/5.1.5/

[SPECTERBLUE]

Could someone help me out with this?

https://stackoverflow.com/questions/72367498/how-to-call-a-method-with-multipuls-arguments-with-different-datatypes-as-input

[SneOG1]

Hi,
I am also a total beginner with OPC UA. I have a kinda similar problem and tried the suggested solution, but the error consists.

I am trying to use call method with two Integer arguments and i am receiving a "BadInvalidArgument"-error.
The code for the method call is as follows:

# Calling a method
        parent = await root.get_child(["0:Objects", "3:ServerInterfaces", "4:Server interface_1", "4:Methods-OPCUA_DB"])
        method = client.get_node("ns=4; i=5")

        input_arg1 = ua.Variant(5, ua.VariantType.UInt32)
        input_arg2 = ua.Variant(4, ua.VariantType.UInt32)

        res = await parent.call_method(method, input_arg1, input_arg2)
    
        print(f"Calling ServerMethod returned {res}")

But i receive following error:

Exception has occurred: BadInvalidArgument
One or more arguments are invalid.(BadInvalidArgument)
  File "H:\Development\Test_OPC_UA\OPC_UA_Client_test_async.py", line 43, in main
    res = await parent.call_method(method, input_arg1, input_arg2)
  File "H:\Development\Test_OPC_UA\OPC_UA_Client_test_async.py", line 49, in <module>
    asyncio.run(main())
asyncua.ua.uaerrors._auto.BadInvalidArgument: One or more arguments are invalid.(BadInvalidArgument)

I am able to call the method in UAExpert. The Server structure is as follows:

and the attributes of the InputParameters are like this:

[prlksk]

[schroeder-]

Error code?

[prlksk]

When I have this: result = device.call_method(method, ua.Variant(0, ua.VariantType.UInt32))
Error:
opcua.ua.uaerrors._auto.BadDecodingError: "Decoding halted because of invalid data in the stream."(BadDecodingError)

when I import : from enum import IntEnum
from opcua import ua
opcua.ua.uaerrors._auto.BadInvalidArgument: "One or more arguments are invalid."(BadInvalidArgument)

[prlksk]