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  1. Forum
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  5. QuickOPC-Classic in COM
  7. Reading, Writing, Subscriptions, Property Access
  9. Read problem

Read problem

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08 May 2019 12:16 #7346 by federica
Replied by federica on topic Read problem
Hi,
thank you very much for your quick responce.

I implemented your solution in our application and I installed it by our customer.
It solved the problem.

I suggested my customer to contact their supplier of the OPC-UA server.
If I receive any feedback, I let you know.

Best regards,
Federica

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24 Apr 2019 05:55 #7332 by support
Replied by support on topic Read problem
QuickOPC provides the data as received from the server. The value, status code, and timestamps come "together" in a Read response. if the server has not returned the right value, the question should primarily be targeted to the server vendor.

You can try to instruct the server to always give you values "from device", preventing it from using any cache. See opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...s%20of%20OPC%20UA%20Nodes.html at the bottom. Basically, in the ReadArguments passed to one of the Read methods, you need to access the ReadParameters object, and set its MaximumAge property to zero.

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

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23 Apr 2019 09:54 #7331 by federica
Read problem was created by federica
Hi,
I'm using your SDK (QuickOPC 2018.1, in particular OPC-UA under COM with C++) since last year.
I'm facing a strange problem from a customer with his OPC-UA server (OMRON).

In order to analize the problem, I'm using your application "EasyOpcUADemo".


"Browser servers..." shows the OPC-UA server without problems.
"Browse data..." shows available variables without problems.
I specify "Value to write" and press "Write value": no problem.
I press "Subscribe" and fields on the right ("Value", "Status", "Source timestamp" and "Server timestamp") update.

But:
If I press "Read", only "Server timestamp" updates while "Value", "Status" and "Source timestamp" doesn't update and preserve the old value.
I receive no exception.

If "EasyOpcUADemo" is subscribed, my application read the variables (with "Read" method) without problem.

Have you any idea?
What could be the problem?

Thank you!

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Moderators: support
  1. Forum
  3. Discussions
  5. QuickOPC-Classic in COM
  7. Reading, Writing, Subscriptions, Property Access
  9. Read problem
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