Online Forums

Technical support is provided through Support Forums below. Anybody can view them; you need to Register/Login to our site (see links in upper right corner) in order to Post questions. You do not have to be a licensed user of our product.

Please read Rules for forum posts before reporting your issue or asking a question. OPC Labs team is actively monitoring the forums, and replies as soon as possible. Various technical information can also be found in our Knowledge Base. For your convenience, we have also assembled a Frequently Asked Questions page.

Do not use the Contact page for technical issues.

Demo Application - Subscription failed: AccessDenied

Start
Prev
1
Next
End

1

roburtm
Topic Author
Offline
Senior Member

More

24 Jan 2022 15:13 #10565 by roburtm

Replied by roburtm on topic Demo Application - Subscription failed: AccessDenied

Yes, we only found a solution for Titanium OPC.

As you can see in previous posts, QuickOpc fails to subscribe with AccessDenied exceptions.

Please Log in or Create an account to join the conversation.

support
Away
Moderator

More

24 Jan 2022 13:04 #10564 by support

Replied by support on topic Demo Application - Subscription failed: AccessDenied

Hello,
thank you for update.

Are you saying that you have found a solution with "Titanium OPC" only, or that you also have found some solution with QuickOPC?

Notes:
1. QuickOPC already calls CoInitializeSecurity, and its arguments can be influenced by the parameters I have provided.
2. Due to some changes Microsoft is doing (support.microsoft.com/en-us/topic/kb5004442-manage-changes-f...52-c141-43d2-941e-37ed901c769c ) there will probably be more options to tweak, in QuickOPC 2022.1 version.

Regards

Please Log in or Create an account to join the conversation.

roburtm
Topic Author
Offline
Senior Member

More

21 Jan 2022 11:22 #10563 by roburtm

Replied by roburtm on topic Demo Application - Subscription failed: AccessDenied

We found a solution for the problem - kind of.

We also tried the open source OPC library "Titanium OPC" which exactly had the same problem when not calling the "Bootstrapper.Intialize()" method, which is equivalent to calling "CoInitializeSecurity".

Please Log in or Create an account to join the conversation.

support
Away
Moderator

More

17 Jan 2022 08:23 #10540 by support

Replied by support on topic Demo Application - Subscription failed: AccessDenied

Hello.

Unfortunately there isn't much else, and nothing specifically targeted.

Possibly revert the changes you made, and then try different settings of

EasyDAClient.ClientParameters.UseCustomSecurity
EasyDAClient.ClientParameters.TurnOffActivationSecurity
EasyDAClient.ClientParameters.TurnOffCallSecurity

(can only be done *once* in the program run, before any OPC operation is attempted)

Related info:
- www.opclabs.com/forum/connections-reconnections-com-dcom/124...ng-to-remote-machines-via-code
- kb.opclabs.com/COM_settings_in_OPC_Classic_client_components

And, combine it with further DCOM tweaking... Sorry, I have nothing better.

Best regards

Please Log in or Create an account to join the conversation.

roburtm
Topic Author
Offline
Senior Member

More

07 Jan 2022 07:53 #10533 by roburtm

Replied by roburtm on topic Demo Application - Subscription failed: AccessDenied

Thank you for the suggestion. Today, we tried the managed implementation but neither the Read, nor the Subscribe do work.

See the attached screenshots for details.

Anything else I can try?

Please Log in or Create an account to join the conversation.

support
Away
Moderator

More

05 Jan 2022 09:55 #10530 by support

Replied by support on topic Demo Application - Subscription failed: AccessDenied

Hello.
can you please unpack the attached file, place the resulting appsettings.json file alongside the EasyOpcNetDemo.exe , and retest?

Explanation: QuickOPC contains two low-level implementations of OPC DA client code. Sometimes the default implementation differs in DCOM-related settings. This configuration file tells QuickOPC to use a second implementation, written completely in managed code (the default one is a mixed mode C++/CLR).

Best regards

File Attachment:

File Name: Appsetting...ssic.zip
File Size:0 KB

Please Log in or Create an account to join the conversation.

roburtm
Topic Author
Offline
Senior Member

More

04 Jan 2022 10:51 #10529 by roburtm

Replied by roburtm on topic Demo Application - Subscription failed: AccessDenied

Thank you for your quick reply.

Reading/writing works in the QuickOPC Demo application. Only "subscribe" fails with the given exception.

Please Log in or Create an account to join the conversation.

support
Away
Moderator

More

04 Jan 2022 09:54 #10528 by support

Replied by support on topic Demo Application - Subscription failed: AccessDenied

Dear Sir/Madam,
thank you for your interest in our products.

Can you please tell me whether Read works in the QuickOPC demo application? If not, what error does it give?

Note: Sometimes, DCOM settings that work with one client do not work with other. I think you are already observing this, because the Async reads should work (in QuickClient), and the fact that they don't may be related to the fact that essentially the same mechanism is used for subscriptions as well as for async methods.

I do have some guidance/recommendations but that will depend on your answer to the question at the beginning.

Thank you

Please Log in or Create an account to join the conversation.

roburtm
Topic Author
Offline
Senior Member

More

03 Jan 2022 14:04 #10527 by roburtm

Demo Application - Subscription failed: AccessDenied was created by roburtm

Hello,

we are evaluating EasyOPC.NET to access data on an OPC DA server at a customer site with .NET.

The DCOM configuration *should* be okay, since we instructed the opc server manufacturer to configure the server/client properly.

We tested the configuration using the "OPCExpert" Tool, as well as the "Kepware OPC QuickClient" and the connection and also subscriptions are working.
The "OPCExpert" Tool works 100%, the QuickClient looks like it works, but we're not 100% sure if it uses subscriptions. Async Reads do not work there, though.

Then, we were installing the "EasyOPC.NET Demo" and connecting/reading works, but subscribing to a value does not work. Of course we're testing on the same machine with the exact same login.

Please see the following screenshot. (On the right side, you can see the "OPCExpert" Tool with its log messages).

How can we diagnose further why EasyOPC.NET cannot subscribe?

Thank you.