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How to add subscriptions?

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14 Dec 2018 20:32 #6922 by support
Replied by support on topic How to add subscriptions?
Thank you. We are aware of the issue, it just have not made its way to the development yet.
Will consider bumping up the priority of this.

Thank you, and best regards

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14 Dec 2018 10:16 - 14 Dec 2018 10:18 #6918 by Boris
Replied by Boris on topic How to add subscriptions?
Thank. Now we use the second option that you suggested. It works. On the Internet, you can find a sufficient number of OPС-UA servers that limit the number of monitores items per subscription. For example, the test server Unified Automation UAAnsiCServer by default also has a limit of 1000 monitored items. Do you plan in the future to add an option that limited the number of monitored items per subscription? That QuickOPC automatically created subscriptions for exceeding the specified limit. That would be very convenient.
Last edit: 14 Dec 2018 10:18 by Boris.

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14 Dec 2018 09:14 #6917 by support
Replied by support on topic How to add subscriptions?
Hello.

QuickOPC puts together monitored items with the same subscription parameters into the same subscription automatically. This is normally an advantage, but in this case it works against you.

Unfortunately there is no direct way to achieve what you want, but there are some possible workarounds:

1) Set the Isolated property on the EasyUAClient to 'true', and use separate EasyUAClient object instances for the "groups" of monitored. This will work, but the effect is not precisely what you asked for. It will create a separate *session* for each such object, with its own set of subscription. If you have, say, two or three such sets and therefore 2-3 sessions, it would probably not be a problem, but with larger numbers, the sessions are "heavier" than just subscriptions, so it may create unwanted load on the server (and to some extent, on the client as well). I'd rather recommend option 2) below.

2) Somehow vary the parameters of the monitored items that affect the subscription - but without big influence on the actual outcome. For example, if you have 2000 items that you want to subscribe to with 500 milliseconds rate, change the code so that it will subscribe to 1000 items with 500 milliseconds rate, and another 1000 items with 499 milliseconds rate. QuickOPC will currently see this as different parameters, and will create two subscriptions.

I hope this helps.
The following user(s) said Thank You: Boris

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13 Dec 2018 14:47 #6915 by Boris
Hello.
For some time, we successfully use QuickOPC-UA for COM in our projects. But now we are faced with a problem when working with the OPC UA server for S7-1500 CPUs. The fact is that this server has a restriction: no more than 1000 monitored items per subscription are allowed. This limitation is described on the official website of Siemens ( here is the link ). The OPС server developers claim that if more than 1000 monitored items are needed, then you need to create an additional subscription and add the remaining monitored items to it.
Hence the question: how can I create multiple subscriptions using QuickOPC?
Thank.

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