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TN AppSvr120 Accurate IO Count Using Dynamic IO Assignment

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When using Wonderware System Platform/Application Server, it is not clear as to the number of IO you are using against your license.

This article shows how to accurately determine how much IO is really being used in a galaxy when dynamic attribute IO assignment is being used.


  • Author: Lewis Talley
  • Published: 03/27/2015
  • Applies to: System Platform 2014 R2




The built in license info does not reflect any IO that is assigned in runtime as shown below:  We have configured 35 IO, not 4.

License Info Display.png


We will need to Historize the attribute ItemCnt for each topic defined in a DDE/SL Client as shown below: So in this case we will be logging 2 values to History Tagname.ItemCnt and TestTopic.ItemCnt

DDE SL Topics.png

Historize ItemCnt.png


Once this is complete and the objects are re-deployed we can easily query the Wonderware Historian to produce the results as shown below:

SQL Query.png


This query (shown below) is used against the Live object, and could be modified to use History if you wanted to see IO over time.

Select sum(Value) as 'Total Active IO Count' from Live

where tagname like '%.ItemCnt%'