Data Access View has different data than Attributes tab

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tbnguyen
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Data Access View has different data than Attributes tab

Post by tbnguyen »

Hello,
I am implementing a simple OPC UA server that reads nodes from another server and sends this data to an OPCUA client, e.g, UaExpert. I have implemented my own readValues, writeValues and other required functionalities to read and view data from an OPC UA node. But in UaExpert, while the data shown in Attributes tab is consistent, the data shown in the Data Access View does not have Value and Datatype (NULL). The timestamps are also not consistent with the timestamps shown in the Attributes tab. Could someone give me some hints on this issue? Which function is actually called to get data and show it in the Data Access View and I drag and drop a node onto it?
Here is the picture of the screen. Image

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Support Team
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Re: Data Access View has different data than Attributes tab

Post by Support Team »

Hi,

DataAccess View is subscribing for data change notification (CreateMonitoredItem, Publish, etc.)

If DAView shows NULL and no Value, most likely never received any data for this node. You should check you implementation and the log window of UaExpert for errors that may have occured when adding the node to the subcription.

There is a pretty deep example in the tutorial of our SDK that shows how to connect node to real world data.
Best regards
Unified Automation Support Team

tbnguyen
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Re: Data Access View has different data than Attributes tab

Post by tbnguyen »

Thank you for your quick reply. I have checked the UaExpert logs but there are no errors. What I do not understand is that the data has been read and displayed correctly in the Attributes tab. I also debug and look into the readValues and dataType() functionalities and check that the datatype and value were read correctly as well. I follow the instruction in https://documentation.unified-automation.com/uasdkcpp/1.5.6/html/L3GettingStartedLesson03.html#Less03NmBuildingAutomation_Cls_Def

tbnguyen
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Joined: 08 Dec 2022, 18:11

Re: Data Access View has different data than Attributes tab

Post by tbnguyen »

In the meantime, I have figured it out. Thank you for your support!

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