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10/18/2019
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- Result Variable in address space and it's reported as Data Change Notification
- Result event and it's reported as Event notification
05/30/2017
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Did you build the Server?
The ability to detect a data change depends on the architecture of the server. Some servers may not be true exception based.
Server may not be detecting a change in the timestamp so it assumes the change is a duplicate.
If there are multiple threads involved the "older" change could arrive before the newer change and be dropped.
Can you slow down the changes see if it works?
10/18/2019
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Hi Randy,
Thank you very much for the response.
I developed the OPC UA Server using a commercial SDK and am using the relevant SDK API to update the Data Source value.
The timestamp between three Results is around 3-5 milliseconds and all three values are generated one after one as I am simulating those in the code for testing.
I will try to check if slowing down works, but even if it does, I was confused that the same thing was working with Event Notifications but was only a problem in Data Change Notifications even after setting a very low sampling and publishing interval on the Server.
05/30/2017
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DataChanges are different from events because only changes are reported. This means you have different logic executing which could mean different behavior in the edge cases.
You should set the SamplingInterval to 0. If accepted the Server is treating data changes like events. If it is raised to some no zero value the Server is telling samples that come too fast will be dropped.
10/18/2019
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Thank you Randy. When i added the delay of 50 ms, it worked.
Sampling Interval set to 0 even in the SDK settings did NOT work. For time being, I will use 50 ms as the elapsed time for data change of same Variable.
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