Hello,
After specifying the OPC UA server using an IP address instead of localhost, I can retrieve the nodes properly. Thank you!
I have another question.
It seems that the node structure retrieved by UAExpert and QuickOPC is different. Is this expected? I'm trying to retrieve registered nodes, but they don't seem to be visible.



Best Regards,

I have two more questions:

1. Internally, is it correct that the source code handles SecurityPolicy (e.g., Basic256Sha256) and MessageSecurityMode (e.g., Sign) automatically without explicit configuration?
2. Is there a specific way to handle the opc.tcp://::1:4841/hahaha/ part using the QuickOPC library?

Best Regards,

To elaborate, I currently have an OPC UA server.
The OPC UA server is using the Security Policy: Basic256Sha256, and the Message Security Mode: Sign.
I can successfully connect to servers with the general Security Policy, Message Security Mode: None.
However, I'm unable to connect to servers where the Security Policy and Message Security Mode have been set (although connection works fine with UAExpert).
I believe there might be additional configurations needed in the source code, but I'm finding it difficult to locate the relevant information in the manual or online forums.

To answer your questions:
1. I am using QuickOPC version 5.70.1053.
2. I am using .NET6.
3 & 4. I will provide the complete log for reference.


Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.


OpcLabs.EasyOpc.UA.OperationModel.UAException: An OPC-UA operation failure with error ID 'OpcLabs.UAEngine=4403' occurred, originating from '' and with depth of 1. The inner exception, of type "OpcLabs.EasyOpc.UA.Engine.UAEngineException", contains details about the problem.
---> OpcLabs.EasyOpc.UA.Engine.UAEngineException: Cannot preselect the best (or any) endpoint for OPC-UA client session. No suitable endpoint has been found. The server returned 1 endpoint(s).
There are several configurable settings that influence which endpoints are eligible for selection, such as the endpoint selection policy, and also parameters that influence how thorough checks of the information returned by the server are made. You may need to change the endpoint selection policy, or the additional parameters, in order to be able to connect. If you are unsure about what is causing all endpoints to be rejected, analyze the log entries generated by the component.
Candidate selection report follows.
[0:NotEligible(EndpointUrl("opc.tcp://::1:4841/hahaha/", NotAllowed(Scheme)))].
+ Connection attempt #1; last connected at 0001-01-01 오전 12:00:00 (local); unconnected for 00:00:00.
+ The client method called (or event/callback invoked) was 'BrowseMultiple[1]'.
--- End of inner exception stack trace ---
at OpcLabs.EasyOpc.UA.IEasyUAClientExtension.Browse(IEasyUAClient client, UABrowseArguments browseArguments)
at OpcLabs.EasyOpc.UA.IEasyUAClientExtension.Browse(IEasyUAClient client, UAEndpointDescriptor endpointDescriptor, UANodeDescriptor nodeDescriptor, UABrowseParameters browseParameters)
at OpcLabs.EasyOpc.UA.IEasyUAClientExtension.BrowseDataNodes(IEasyUAClient client, UAEndpointDescriptor endpointDescriptor, UANodeDescriptor nodeDescriptor)
at OPCUAWebRESTAgent.OPC.BrowseDataNodes.BrowseFromNode(EasyUAClient client, UAEndpointDescriptor endpointDescriptor, UANodeDescriptor parentNodeDescriptor) in C:\dev\work\opc\workspaces\OPCUAAgent\OPCUAWebRESTAgent\OPCUAWebRESTAgent\OPC\BrowseDataNodes.cs:line 63
at OPCUAWebAgent.Controllers.EndpointRESTController.GetNodeChildren(Int32 id, String endpointId, String parentNodeDescriptor) in C:\dev\work\opc\workspaces\OPCUAAgent\OPCUAWebRESTAgent\OPCUAWebRESTAgent\Controllers\EndpointRESTController.cs:line 169
at lambda_method163(Closure , Object , Object[] )
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Hello. Could you please guide me on how to connect to or read from an OPC UA server with a securityPolicy(ex:Basic256Sha256) applied?
Specifically, I'd appreciate it if you could explain how to retrieve data using the BrowseFromNode method.
With the existing source code, I can fetch data and node information well from servers without a securityPolicy applied.

Source code:
var client = new EasyUAClient();
...
if (parentNodeDescriptor != null) nodeElementCollection = BrowseDataNodes.BrowseFromNode(client, endpoint.URI, nodeDescriptor);
else nodeElementCollection = BrowseDataNodes.BrowseFromNode(client, endpoint.URI, UAObjectIds.ObjectsFolder);

ERROR: "There are several configurable settings that influence which endpoints are eligible for selection, such as the endpoint selection policy, and also parameters that influence how thorough checks of the information returned by the server are made. You may need to change the endpoint selection policy, or the additional parameters, in order to be able to connect. If you are unsure about what is causing all endpoints to be rejected, analyze the log entries generated by the component.
Candidate selection report follows."

Best Regards