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Reading value takes up to 30 seconds

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28 Oct 2011 09:58 #583 by owe@eurosys.se
Hi!
I've used both ReadItem / ReadItemValue. With Itemvalue i've polled 15 time, sleeping 200 ms between. It works with many of the request but once a while it doesn't get any value in this timelimit. It also works with read item but i have to wait up o 10 seconds to read an int.
The opc supplier says there is nothing wrong in their end. They have checked in their browser and the quality is good. I'm stucked and doesn't now what to try next. It works find though when testing off business hour, with no load in the system.
I create a new instance of EasyDAClient for every read I do. Could that be the problem?
>Regards Owe

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21 Oct 2011 10:09 #570 by support
Version 3 is no longer supported. From what I remember, it is either similar in Version 3, or instead or in addition to the method in Version 5, you could also pass the ClientMode as one of the arguments to the ReadXXXX method. It would be in the documentation.

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20 Oct 2011 13:29 #569 by owe@eurosys.se
THANKS!

About quality=28 we receive it one hour after the production has started. I though know tht you can't affect
the value. I just wondered what it mean?
About "Set ClientMode.DataSource" . Is it the same in QuickOPC version 3?

Thanks for answering this quickly.
>Regards Owe

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20 Oct 2011 12:56 #568 by support
Bad qualities (or any qualities...) are created by the OPC Server. The component never creates its "own" data quality, and it never modified a data quality that it had received from the OPC Server. So, the answer has to be figured out in the server.
One of the possibilities is that the server is too busy or starting up and does not have the value yet.

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20 Oct 2011 12:53 #567 by support
If you need to assure that you get the value from the device, and not cached, you need to specify it. Set ClientMode.DataSource to Device.

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20 Oct 2011 12:48 #566 by support
You do not say what kind of problems with writing you have.
The purpose of hold periods is simple - the component keeps items/servers connected for some time, should the same item be needed again soon. So, the proper setting of the hold periods depends on the timing used by your application to access items. If, for example, you access the same set of items once per minute, and it is just a handful of items, it may be wise to let the connections open all the time, in which case the proper hold periods will be greater than one minute.

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20 Oct 2011 12:11 #565 by owe@eurosys.se
Hi!

It has become quite urgent for me to solv this issue with quality=28.
I've read that this is because of the the tag is inactive.
How do I get it active all the time?
Hold periods?
>Regards Owe

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20 Oct 2011 09:19 #564 by owe@eurosys.se
Hi!

When I logged the quality received when getting zero it was 28, eg "Out of service". Do you have any idea of the cause regarding this quality. Maybe this is the explanation for the whole mess above?

>Owe

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20 Oct 2011 06:05 #563 by owe@eurosys.se
Hi again.
We are now running the system in the old enviroment with QuickOPC 3.0. We got some problems there too now.

PLC writes a numeric value in tag "Workorder" and trigger us on tag PLC_Event.

We react and tries to read the Workorder with ReadItemValue. When the response comes back i've got value zero in return which the plc guy says not is true. Because of this zero value the system doesn't know what to do and must throw an exception.
Do you have any idea of how to investigate this on our side.

>Regards Owe

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20 Oct 2011 04:36 #562 by owe@eurosys.se
Hi!

Thanks. As opposed to the caption I think we have the most problems with writing.
If I use WriteItem and WriteMultipleItems we can be quit the problem?
It's quit a busy system. Do you have any guidlines about setting with HoldPeriods and so on in this kind of system. Today we use the default values.

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