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XML-DA. Disable advanced polled refresh

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31 Mar 2020 08:10 #8335 by support
QuickOPC 2020.2 will have an option to switch to basic polled refresh approach. See kb.opclabs.com/What%27s_new_in_QuickOPC_2020.2 for more information.

Expected release date is 1-3 weeks.

Regards
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11 Mar 2020 14:17 #8289 by support
I will discuss the proposed workaround with the developer and if possible, put it into the upcoming versions (2020.2).
Good news are that we are finalizing one large (unrelated) functionality area, so there in fact might be 2020.2 release in matter of weeks (this is not a promise, though).

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11 Mar 2020 09:53 #8283 by Andriy
Hello,
Nordex OPC XML-DA server
Unfortunately, this functionality can not be easily adjusted on the server side
Regards

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10 Mar 2020 12:43 #8280 by support
Who has developed the server and what protocol/software is it for?
Why don't you ask them to fix it?

If an attribute in a request is optional, it means that the send may or may not include it. It also means that the server must be ready to handle both situations, unless the specification allows for different behavior on server side. Everything the the specification describes is mandatory for the server unless specified optional. Otherwsie, the specification would be useless.

We do not do specific implementation work for pay.

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10 Mar 2020 10:11 #8278 by Andriy
Hello
I don't quite agree with you. According to the description of SubscriptionPolledRefresh request, the attribute "HoldTime" is optional. It means that opc client must implement basic polled refresh approach with delaying on the client side.

Anyway, how much can it cost to speedup implementation?

Regards
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07 Mar 2020 01:35 #8273 by support
Who has developed the server and what protocol/software is it for?

I am hesitant to do extra work on an obsoleted protocol for free just to fix a problem that should really be fixed on the server side. If we decide to do it - which is not sure - it will have to go to next version, not to the existing one. There is no date scheduled for the next version yet.

And it needs to be thought through. It cannot be in instance parameters because multiple instances (if they have Isolated = false) share the same subscriptions. It would have to be in EasyDAAdaptableParameters.

Regards

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06 Mar 2020 17:45 #8271 by Andriy
Hello,

It can a patch that allows me to configure opc client instance parameter "PolledRefreshDelay" in msec.
It should delay next SubScriptionPolledRefresh call for active group.
PolledRefreshDelay = 0  - we have a regular behavior (default value)
PolledRefreshDelay = "opc group update rate" - should fix my problem
PolledRefreshDelay should be an instance parameter
Can you do it in this way?

Regards

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06 Mar 2020 16:56 #8270 by Andriy
Hello,
I have a problem. The OPC XML DA server is not supporting sophisticated polling approach and looks like will never do.
What is needed to implement waiting approach on the client side rather than delegate it to the server?
Maybe you know a trick how to delay SubscriptionPolledRefresh call.
I need the solution ASAP

Regards

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26 Feb 2020 13:32 #8250 by support
This cannot be changed in QuickOPC.
AFAIK, all OPC XML-DA servers must support it.
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26 Feb 2020 11:12 #8249 by Andriy
Hello,

I figure out that opc library is using sophisticated polling approach passing "Holdtime" and "Waittime" parameters in SubscriptionPolledRefresh call.

I hove a trouble with one of OPC XML-DA server that does not perform a delayed poll and sends an answer immediately.
Can I disable this behavior and delegates the waiting to the client side instead?

Regards
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