tbischoff2
commented
4 weeks ago I'm not sure, if attaching the text files worked. So, here is the code of the Python OPC UA Server:
from asyncua import Server, ua import asyncio
async def main(): server = Server() url = "opc.tcp://localhost:48010" await server.init() server.set_endpoint(url) name = "testNamespace" addspace = await server.register_namespace(name)
objects = server.nodes.objects
async def TestOperation(parent, input):
return [ua.Variant(input.Value, ua.VariantType.String)]
myobj = await objects.add_object(addspace, "MyObject")
input_argument = ua.Argument()
input_argument.Name = "Input"
input_argument.DataType = ua.NodeId(ua.ObjectIds.String)
input_argument.ValueRank = -1
input_argument.ArrayDimensions = []
input_argument.Description = ua.LocalizedText("Input-String")
output_argument = ua.Argument()
output_argument.Name = "Output"
output_argument.DataType = ua.NodeId(ua.ObjectIds.String)
output_argument.ValueRank = -1
output_argument.ArrayDimensions = []
output_argument.Description = ua.LocalizedText("Output-String")
mymethod = await myobj.add_method(addspace, "TestOperation", TestOperation, [input_argument], [output_argument])
await server.start()
print(f"Server started at {url}")
while True:
await asyncio.sleep(1)if name == "main": asyncio.run(main())
kevinherron
We have an application with an OPC UA client based on Milo. Now, one of the users had problems with a method in an OPC UA Server based on Python opcua-asyncio: https://github.com/FreeOpcUa/opcua-asyncio It's a method with 1 input and 1 output argument, both of type String (see attached screenshot of UaExpert).
But Milo has problems reading the input and output arguments of the method. To reproduce the problem, I modified the MethodExample2 from the client-examples project of Milo (current version of the master branch), And I also had to modify 2 methods of the "ClientExample" file:
That's the modified run method of MethodExample2:
The method "logArguments" doesn't find input or output arguments: 09:46:50.929 [main] INFO o.e.m.examples.client.MethodExample2 - Input arguments: none 09:46:50.929 [main] INFO o.e.m.examples.client.MethodExample2 - Output arguments: none
After that, when I call the mehod "readInputArgumentsAsync" an exception occurs (see attachment).
The method of the Python OPC UA Server works normally with other clients or SDKs.
To reproduce the problem, you need Python with the package asyncua: pip install asyncua
After starting the server (python server.py), it's running with this endpoint: opc.tcp://localhost:48010 I also attached the Python file with the OPC UA Server (just rename the "server.txt" to "server.py").