Emerson Exchange 365

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OPC UA Server to Client notification of new data for upload

Hello All,

We are in the process of developing an OPC UA Server stack for a new instrument to upload measurement data to the Client.  Due to the nature of the measurement, new data would be available no sooner than 5 minutes from the previous measurement, and potentially at much longer intervals depending on the user settings for sample intervals.  We are not currently looking to have the Client trigger a measurement, but would like to know if there a function within the Server protocol to alert the Client that new data is available.  If so, could you please point me to some documentation on how to implement that functionality?  Also, is there a mechanism for the Server to be notified that the data has been received by the Client?

We are considering either Python or C++ for development.  

Thank you,

John

John Barnacle

• 29 Jan 2021 5:14 PM
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2 Replies

• Lun.Raznik

  

  • 29 Jan 2021 6:04 PM

  RE: Server protocol to alert the Client that new data is available
  Yes. This is part of the subscription model, see below for reference
  reference.opcfoundation.org/.../
  documentation.unified-automation.com/.../_l2_ua_subscription.html
  
  Using Python AsyncIO library, see below, shows how a very simple update rate was accomplished, see line 39
  github.com/.../server-minimal.py

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• Lun.Raznik

  

  • 29 Jan 2021 6:09 PM

  In reply to Lun.Raznik:

  RE: is there a mechanism for the Server to be notified that the data has been received by the Client?
  The server gets a notification of receipt of the data from the client as part of the publish service

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