History Trend View

Questions regarding the use of the UaExpert.

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History Trend View

Post by ekjcheng »

Dear Sirs (Unified Automation Support)

I am new to using the UA Expert. I have a simple Counter program done in Codesys
I tried to drag counters in Access View and their was no problem seeing the live Counter values increasing.

I tried to also drag the same counter into History Trend View and I receive the message in log: Added Item does not support Historizing. What kind of items support Historizing?

Kindly advise what I should do. Thank you

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Support Team
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Re: History Trend View

Post by Support Team »


the history trend view in UaExpert can read out and display the data that is historized in the UA server. The Codesys UA server oviously lacks such OPC UA serverside feature completely (or at least for the nodes you are trying). You can identify the presence of historic data of a particular node in the address space of the server by reading out the attributes of such node (see attribute window in UaExpert). If you find the attribute "historizing=true" the UA server has (besides the actual value) stored some historic values for this particular node.

When drag & drop the node into the UaExpert's historic view window, the UaExpert checks in the background if the particular node provides historic data. In your case that is obviously not the case (probably because the Codesys is missing such feature).

In OPC UA terminology:
1) "Historic Data Access": means the client can access historic data that is available in the server (recorded even during the absence of the client)
2) "Data Logging": means the client is subscribing for actual data and is storing/logging values of interest itself over the period it is connected with the server.
Best regards
Unified Automation Support Team

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