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  1. Forum
  3. Discussions
  5. QuickOPC-Classic in .NET
  7. Reading, Writing, Subscriptions, Property Access
  9. XML-DA. Control the number of subscriptions.

XML-DA. Control the number of subscriptions.

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02 Mar 2020 15:50 #8259 by support
Replied by support on topic XML-DA. Control the number of subscriptions.
Quote from my post: "currently on our Web site".
Not all builds go to NuGet.

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02 Mar 2020 15:40 #8258 by Andriy
Replied by Andriy on topic XML-DA. Control the number of subscriptions.
Hello,

I don't see version x.xx.96.1. Last available version on nuget is 5.57.83
Best regards

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29 Feb 2020 16:18 #8252 by support
Replied by support on topic XML-DA. Control the number of subscriptions.
Hello.

Please use the newest build (96.1, currently on our Web site, or later) of QuickOPC . The bug should be fixed now.
Thank you for reporting it.

Best regards
The following user(s) said Thank You: Andriy

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25 Feb 2020 10:04 #8244 by support
Replied by support on topic XML-DA. Control the number of subscriptions.
I am forwarding this to the developer who worked on this part of code.
QuickOPC is supposed to put items with identical GroupParameters into the same group.
Hopefully he will be able to reproduce it. If not, we will ask for more info or reproducible steps.

Best regards
The following user(s) said Thank You: Andriy

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25 Feb 2020 07:13 #8243 by Andriy
Replied by Andriy on topic XML-DA. Control the number of subscriptions.
Hello

Sorry for the delayed response.
1. Yes. QuickOPC creates separate groups even for items with the same subscription parameters.
2. No. Subscription parameters are the same for all items

1.My application can unsubscribe from unused items and subscribe to them again during its lifetime.
2.Monitor about 100-200 opc tags
3.Limit the number of HTTP client connections allowed:
EasyDAClient.AdaptableParameters.HttpClientConnectionLimit = 2;
Is this a bug in the QuickOPC library? Can you fix it?

Regards

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18 Feb 2020 15:25 #8232 by support
Replied by support on topic XML-DA. Control the number of subscriptions.
If you need to subscribe to some items at the same rate (and with other subscription parameters being the same), one OPC group for all of them is normally what should be used. And, QuickOPC should take of that automatically, putting all such items into one OPC group.

So, are you saying that this is not happening? Thatis, that QuickOPC creates separate groups even for items with the same subscription parameters?
Or why do you have 10 different OPC groups? Have you made the subscription parameters intentionally different on the items? If so, why?

Regards

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18 Feb 2020 15:02 #8231 by Andriy
XML-DA. Control the number of subscriptions. was created by Andriy
Hello

Do you have the ability to control the number of subscriptions created by the opc library on the OPC XML-DA server?
My application is flooding XML-DA server, polling for changes about 10 different OPC groups every second.
I have to figure out how to reduce the number of polling requests.
One of the solution is to integrate several subscriptions into larger one.
Another solution is to try polling several opc groups at once (supplying multiple opc group handles in element "ServerSubHandles" of SubscriptionPolledRefresh request)
According to the XML-DA spesification:
Multiple ServerSubHandles may be supplied. The server will respond with the changes in data associated with all supplied ServerSubHandles
I'm not sure if opc server supports this feature, but it also worth to try it
Do you have any suggestion?

Regards

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  1. Forum
  3. Discussions
  5. QuickOPC-Classic in .NET
  7. Reading, Writing, Subscriptions, Property Access
  9. XML-DA. Control the number of subscriptions.
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