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System goes slower and slower

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23 Nov 2011 17:13 #657 by support
Yes, I think you have made the right settings, at least with the first two. The last one is just a default for your explicit subscriptions, if you have omitted the UpdateRate parameter to the SubscribeXXXX method call, otherwise it'll have no effect (and Version 5.x does not have this setting at all), and is not related to this problem.
The expected behavior with this setting is that the number of Active Tags will still increase after you Read something, but because these tags are not really active, they should not slow down the system (or, at least, not as much as before the settings were changed). And, each such Active Tag should be automatically removed after a period of time - this is the "Hold period" labeled "After topic read", and it defaults to 120000 (two minutes). There is a property for it as well, and if these inactive tags still cause a problem (and you do not expect be read again soon after the first read), you can also decrease this hold period, even significantly.
Regards,

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23 Nov 2011 09:26 #655 by owe@eurosys.se
Hi again!

We will start testing the new settings tomorrow. I made these changes to the EasyDACOM object (the old version). Do you think these ares the same as in the new version?

Should the number of Active Tags in the OPC-server increase for every new tag I read or how does it works with the "Internal subscribes" you talked about?

.DefaultMode.ReadValueAutomaticUpdateRate = -1;
.DefaultMode.ReadAutomaticUpdateRate = -1;
.DefaultMode.ManualUpdateRate = -1;

>Regards Owe


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15 Nov 2011 12:55 #617 by owe@eurosys.se
OK

Though it works when using local instance in the method and not a global one it seems
to be in my code somewhere. And as you said, one static instance versus local instances
in methods shouldn't affect performance very much.

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14 Nov 2011 20:02 #616 by support
Both are supposed to be threadsafe in the sense that confusing Item Ids as you described it should never happen - and I am not aware of such problem.
Being thread-safe, though, does not guarantee order of operations with respect to the OPC server, e.g. if two threads call two methods in sequence without waiting for the operation being completed, the actual order in which they are executed is not defined.

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14 Nov 2011 13:26 #613 by owe@eurosys.se
OK.

Both the old and new versions are threadsafe or? It's OK to have one static instance?
One peculiar thing we have in both versions is that if a couple of threads writes
at the same time, it seems like the first writes OK, but the upcoming threads misses to write
to the correct itemID. It writes to the itemId from one of the others threads.

Is this anything you know about? It didn't seem to happen if I write to a locally instantiated
instance in my method.

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14 Nov 2011 12:31 #612 by admin
Yes, in every instance after creating it.

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14 Nov 2011 12:18 #611 by owe@eurosys.se
Great.

When I create a new Instance, should I set this property every time on the new Instance, or is there
another way?
>Owe

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14 Nov 2011 10:34 #610 by support
This looks like the same property in 3.0x. I think that setting it to the same thing (Infinite) or -1 will do.
Subscribing to all tags would only make matters worse.

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14 Nov 2011 08:59 #609 by owe@eurosys.se
Thanks!
We had to go back to the older version of QuickOPC, 3,2, because it works slightly better with this at the moment. Do you know how
to set this version to Infinite. There is a property ReadValueAutomaticUpdateRate We will try the new version again when my customer has time for it with their production.

Could Subscribing to all tags also be a solution to the problem?

>Owe

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12 Nov 2011 15:05 #607 by support
The differences between having just one instance and having multiple instances are subtle, and should not have influence on the problem you are seeing.

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