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write then read then monitor - incongruous results

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04 Feb 2015 09:09 #2693 by support
Replied by support on topic write then read then monitor - incongruous results
Great.

The instructions are here:

www.opclabs.com/files/knowledgebase/QuickOPC/QuickOPC-1-How%20to%20use%20OPC%20Analyzer.pdf

And the actual tool is here:

www.opclabs.com/resources/product-information/knowledge-base/category/49-restricted

Best regards

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03 Feb 2015 19:50 #2683 by giles
Replied by giles on topic write then read then monitor - incongruous results
I shall try when i get time many thank

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03 Feb 2015 17:30 - 03 Feb 2015 17:30 #2681 by support
Replied by support on topic write then read then monitor - incongruous results
I suspect that we deliver to you what the server gives to us. But I have no evidence in hand to prove that. Would it be possible for you to put the OPC Analyzer server (which we can provide) in between, and grab the communication trace? This requires to modify the client so that it talks to the OPC Analazer server instead.

How frequently does this happen? And, if we get the communication trace, how would we identify the moment of the incident? Will you know e.g. from your client app the time when things went wrong?

Thank you
Last edit: 03 Feb 2015 17:30 by support.
The following user(s) said Thank You: giles

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03 Feb 2015 17:06 #2680 by giles
Replied by giles on topic write then read then monitor - incongruous results
it's kepware kepserverex talking to allen bradley ethernet

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03 Feb 2015 14:02 #2678 by support
Replied by support on topic write then read then monitor - incongruous results
Which OPC Server are you using please?

Is this issue with "real" tags, or some kind of simulated tags?

Thank you

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02 Feb 2015 22:55 #2673 by giles
write then read then monitor - incongruous results was created by giles
Hi. I am writing with DAClient.WriteMultipleItemValues then pretty much immediately reading back with DAClient.ReadMultipleItemValues the values I wrote.

Then I subscribe with DAClient.SubscribeMultipleItems

however the first values I get back from the subscription is sometimes the value before it was set - and the value that same subscription had previously.

Ie it seems to be holding the subscriptions open but the write and subscribe aren't being synchronised.

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