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Subscribe Problem

  • Peter Siegel
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27 Oct 2011 06:37 #578 by Peter Siegel
Replied by Peter Siegel on topic Subscribe Problem
Thank you very much, that would be great...
Peter

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25 Oct 2011 17:30 #573 by support
Replied by support on topic Subscribe Problem
Unfortunately not. I can put it on priority for next release (expected December to January).

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  • Peter Siegel
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24 Oct 2011 14:42 #571 by Peter Siegel
Replied by Peter Siegel on topic Subscribe Problem
Hello!
Is this Problem already fixed in your latest release?
thanks
Peter

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07 Jun 2011 13:47 #399 by support
Replied by support on topic Subscribe Problem
The new version I was referring to is just in plans; it will not be available sooner than in September. For now, the way to go is the fix I have provided.
I do not understand your question:

I don't understand why there is a problem with big argument arrays when i subscribe for each item individually?

The problem I have described applies both to SubscribeItem in a loop for large number of items, and to SubscribeMultipleItems with large number of items, though with SubscribeItem in a loop it may be worse.

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  • Peter Siegel
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07 Jun 2011 13:38 #398 by Peter Siegel
Replied by Peter Siegel on topic Subscribe Problem
When will this new fixed Version be released?

Will try your fix and report back..
I don't understand why there is a problem with big argument arrays when i subscribe for each item individually?
thank you

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01 Jun 2011 08:28 #394 by support
Replied by support on topic Subscribe Problem
This appears to be an issue with the algorithm that the component uses to make OPC method calls with reasonably-sized argument arrays. With high number of items, when first items are being subscribed, the load on the system increases, causing the algorithm to choose smaller "chunks" for processing, and consequently the whole process takes too long.
In my test, adding following code before the subscriptions are made has helped (you may experience with the 'factor' value):
const int factor = 100;
EasyDAClient.ClientParameters.TopicProcessingIntervalTimeout *= factor;
EasyDAClient.ClientParameters.TopicProcessingTotalTimeout *= factor;
We have an improvement planned for future version of the component which should resolve the issue altogether.
Best regards, Zbynek Zahradnik

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  • Peter Siegel
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31 May 2011 12:08 #393 by Peter Siegel
Replied by Peter Siegel on topic Subscribe Problem
The Items are mainly constant, there will be max 1% change per second. Currently i have 0.07% percent change. But i need to be notified about the changes as fast as possible.
I'm not sure if i get all the update events from the server, but I'm not expecting more events.
So it seems to be working if I subscribe slowly enough. if i subscribe all at once without delay, i'm missing events. In this case i get events from ~25% of the Items.
thank you
Peter

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31 May 2011 08:47 #392 by support
Replied by support on topic Subscribe Problem
Hello,
can you please provide the missing piece:

4. What is the rough percentage of items changing in each update period (e.g. are they mainly staying constant, or - on the other side of the scale - do all or most of them change their value each update period?).

That is, is 40-60 updates currently received per second equal to the actual amount of changes generated by the OPC server, or is the amount generated by the OPC server higher and you are expecting to see more in the client (how much?).
Thank you

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  • Peter Siegel
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30 May 2011 07:54 #391 by Peter Siegel
Replied by Peter Siegel on topic Subscribe Problem
Thank you for you help.
Yes the OPC Server is running on the same machine as the component. The opcdaserver.exe Process (Siemens Simatic.net OPC server) is using 3-5% on average. on a 8 core server. The Server has an average load of 15%.
I Subscribe with a rate of 250 like this:
EasyDAClient.EngineParameters.DefaultEventQueueSize = 99999;
EasyDAClient.EngineParameters.TopicLruSize = 99999;
easyDAClient = new EasyDAClient();
easyDAClient.ClientMode.AllowAsynchronousMethod = false;
easyDAClient.ClientMode.AllowSynchronousMethod = true;
easyDAClient.ClientMode.DesiredMethod = DAReadWriteMethod.Synchronous;
easyDAClient.Timeouts.ReadItem = 50000;
easyDAClient.Timeouts.WriteItem = 50000;
easyDAClient.Timeouts.GetProperty = 36000;
easyDAClient.UpdateRates.ReadAutomatic = 250;
easyDAClient.HoldPeriods.TopicRead = 24 * 60 * 60 * 1000;
easyDAClient.HoldPeriods.TopicWrite = 24 * 60 * 60 * 1000;
easyDAClient.ItemChanged += new EventHandler(easyDAClient_ItemChanged);

EasyDAClient.ClientParameters.LinkCallbackQueueSize = 10000;
easyDAClient.SubscribeItem(hostID, OPCServerID, datapoint.Name,250, datapoint);
I register for 4700 Tags at the moment and get approximately 40-60 updates per second.
It is essential for me that the subscribeitem method has done its work reliably. Is there any way to check if i'm successfully subscribed to an item?
thanks in advance..
Peter

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29 May 2011 10:02 #389 by support
Replied by support on topic Subscribe Problem
Hello,
I can confirm that I can reproduce similar or same behavior.
It is, however, highly dependant on other parameters. Specifically, the update rate of the items. Before I give you further advise, can you please answer the following?

Is the OPC Server running on the same machine as the component, or is it accessed over network?
If it is running locally, how much CPU does the OPC server use?
What is the update rate that you request in the "subscribe" call?
What is the rough percentage of items changing in each update period (e.g. are they mainly staying constant, or - on the other side of the scale - do all or most of them change their value each update period?).

Many thanks
Zbynek Zahradnik

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