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Continuous disconnects and reconnects with Cogent Data hub

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13 Feb 2019 15:45 #7084 by bkell1977
Hi,

There is no issue as such, but our customer is seeing a lot of log messages indicating the connect and disconnect of sessions.

We will investigate the use of subscriptions.

Just to be clear, the component is correctly reading tags and retrieving data.

Thank you for your assistance.

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13 Feb 2019 10:41 #7083 by support
In such case, what you are seeing is likely behavior by design.

QuickOPC connects and disconnects as needed. In fact, it is not clear from your post why connects and disconnects should be any problem.

If you want to prevent them, you have two options:
- Subscribe to something. As long as you are subscribed, QuickOPC will try to keep the connection open.
- Increase the HoldPeriod, see www.opclabs.com/files/onlinedocs/QuickOpc/Latest/User%27s%20...sionParameters~HoldPeriod.html . The default is several seconds, so if your reads are not that frequent, the component will disconnect. You can make it quite long, minutes etc.

Best regards

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13 Feb 2019 10:35 #7082 by bkell1977
Hi,

We just read tag values periodically.

Thanks.

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13 Feb 2019 09:57 #7080 by support
Hello.

Are you using subscriptions, or just call read/write methods form time to time?

Regards

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13 Feb 2019 09:45 #7079 by bkell1977
Hi all,

We have developed an app that uses QuickOPC and we are seeing an issue.

We use the app against Cogent Data hub, but the logs show that we have continuous connects and disconnects of sessions.

I think this is a code architecture issue.

The app is a windows service that creates a QuickOPC object, that object is stored as a property against another object in a list. When we need to use the QuickOPC object, we pass it by reference to the relevant methods.

I believe that this could be the issue, does the QuickOPC object need to be created and used directly, or should it be okay to pass it around the application?

Thanks.

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