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Cyclic subscription
March 26, 2014
13:56, EET
Forum Posts: 43
Member Since:
March 26, 2014
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I just would like to know if it is possible with OPC UA and your Server/Client SDK to have a subscription that would always send the current value of all data subscribed at each publish. This means that even if a value does not change, the client would be notified each seconds for instance of this value.

Or the only way to do this is to use the read method from the client at a fixed rate ?


March 26, 2014
14:57, EET
Jouni Aro
Forum Posts: 960
Member Since:
December 21, 2011
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Read is the only way. The OPC UA specification does not define a way to refresh the complete subscription when the values have not changed.

Subscription.readAll() does this, but may get mixed with the changes coming to the subscription from another thread. So it may be best to just read without a subscription.

I have suggested a new method to Refresh the complete subscription, which would be useful in some situations to ensure that we have all the values up to date. But it will only be available in future OPC UA specifications. And it will still require a specific method call from the client to get the refresh.

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