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Problem with delta temperature in PI AF 2017 R2A

Question asked by Tomas Stark Champion on Feb 2, 2018
Latest reply on Feb 2, 2018 by vkaufmann



we have just upgraded to PI AF 2017 R2A from 2015 R2. Everything seems to work fine, except for one thing.


We have an analysis where a difference between two temperature values is calculated. Both temperature values (Mätvärde, Vattentemperatur) have the UOM "degree Celsius".


For some reason, Variable2 will have the UOM "delta degree Celsius" and the analysis will fail with the message "UOMs 'delta degree Celsius' and 'degree Celsius' must belong to the same class". And they do not belong to the same class, since the classes "Temperature" and "Temperature (Delta)" are defined by OSIsoft as two different classes.


180202 Skärmklipp UOM.JPG


I can't really see the logic in this:

     1. Why is Variable2 forced to have the UOM "delta Celsius"?

     2. In the UOM definitions I can't see anything that connects the classes "Temperature" and "Temperature (Delta)", so how does PI Analytics know that there is a connection between the two UOMs?


180202 Skärmklipp Tätningsbox.JPG