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  5. QuickOPC-Classic in .NET
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  9. Hold Periods. Server Detach meaning

Hold Periods. Server Detach meaning

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14 Aug 2019 09:53 #7625 by support
Replied by support on topic Hold Periods. Server Detach meaning
IOPCItemIO is only available in newer OPC specs, and not all servers implement it. What's more important, it is not meant for efficient access.

I am not completely sure about EasyDAClient.Dispose, but I think it does not force an immediate disconnect.

Best regards
The following user(s) said Thank You: Andriy

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14 Aug 2019 09:39 #7623 by Andriy
Replied by Andriy on topic Hold Periods. Server Detach meaning
Hello,

Thank you for the explanation. I'm not sure that OPC group needs to be added in order to read OPC items. There is IOPCItemIO interface that provide OPC data in simple way.
One more question. When i call Dispose method on the instance of EasyDAClient class, does it mean that QuickOPC disconnects from OPC server(s) immediately cleaning all resources (items, groups, connections)?

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14 Aug 2019 09:02 #7622 by support
Replied by support on topic Hold Periods. Server Detach meaning
In OPC Classic, in order to read from an item, an OPC group needs to be added, and the OC item added to it, and only the the Read call can be made. The "Hold Periods - Topic Read" being 30 seconds means that (if there is no other use for the item and the group), 30 seconds after the read, QuickOPC will remove the item and remove the group. But it stays connected to the OPC server. If there is no need to stay connected, In your example, QuickOPC will disconnect after additional 10 seconds ("Hold Periods - Server Detach".

The actual hold periods you will observer can be a bit longer in the effect, because there is a periodic "garbage collector" task that takes care of detecting what's no longer in use, so nothing gets removed until this tasks kicks in.

Best regards

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12 Aug 2019 06:40 #7617 by admin
Replied by admin on topic Hold Periods. Server Detach meaning
I apologize for delay, it is vacation period. Will reply during the remainder of the week.

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08 Aug 2019 12:29 #7612 by Andriy
Hold Periods. Server Detach meaning was created by Andriy
Hello,

I can't find explanation of "Hold Periods - Server Detach" property (when and how it is used). Can you provide an example?
Suppose, I read one OPC item once. Next 30 sec the connection to OPC server will be maintained by "Topic Read" property.
Does it mean that connection longlivity is 30sec + 10sec if "Server Detach" property has value 10 sec?

Best regards

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  1. Forum
  3. Discussions
  5. QuickOPC-Classic in .NET
  7. Connections, Reconnections, COM/DCOM
  9. Hold Periods. Server Detach meaning
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