Why is there a huge difference in speed between OPC reading tags using the document type to read a large structure and dragging and dropping all the tags inside the structure to create an equivalent amount of tags?

Ignition
1

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I read a huge structure from PLC with OPC ua, the structure is the one shown in image above.
I try two method to read it.
One,I drag "IIOT_01" into Tag provider,then i have a tag named "IIOT_01".

Two,I creat many folders like "1","2","3", and so on,Since the names of the labels at the bottom of the structure are the same I'm going to put them in different folders.
Then I expanded all the layers of the structure, dragged and dropped all the tabs inside into the folders.

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In the end I found that the first method reads the data change in as little as 300 millimeters, while the second method takes 2 seconds.

What are the reasons for such a gap?

2

How are you measuring the speed difference?

In any case, you're describing a subscription to one single tag with a structured value vs a subscription to many tags with scalar values. It's usually more efficient for the embedded server running on relatively low powered PLCs if you subscribe to the structures instead.

For the Ignition client running on PC hardware it does not make a difference.

3

I wrote a script to change the value of the tag in the PLC, and then counted the time it took for the value to change.
one single tag with structured value is much faster than many tags

4

What were the times? What was the unit of measure? Milliseconds? What did you use to do the counting?

5

Time elapsed from writing the value to receiving the change in value after the PLC.