Display single result of Event Frame attributes that are calculations (Average, Total, etc.) instead of underlying tag data
When there is an Event Frame attribute that is calculated, i.e. the attribute has a “By Time Range” Value retrieval method of Total, Average, Maximum, Minimum, etc., PI System Explorer shows a single value for this Event Frame Attribute. In PI Vision displays, however, the underlying time-series tag data are displayed instead of the calculation result. I would like to view the calculated value instead of the underlying tag’s time series data in order to be able to compare values from different Event Frames.
Michael Bollenbacher commented
I've run into the same issue as Laura and would like to see some sort of setting that would add a simple solution to visualize Event Frame data like this. Presently, I have found two workarounds to the issue. The first involves storing the value to a PI Tag, the second does not. In this scenario I wanted to show the maximum attribute value during the Event Frame.
For the first method, create an output expression in the Event Frame Generation using the TagMax function with the element attribute in question along with the start and end time of the Event Frame like this TagMax('Att', EventFrame("StartTime"), EventFrame("Endtime")). By linking this to an Event Frame attribute and displaying it in PI Vision the correct value can be visualized. This method was suggested by Tech Support and works if you don't mind storing an additional PI Tag.
For second method, you'll need to create two Event Frame attributes. The first attribute will be a Pi Point Data Reference with a By Time setting of Automatic and By Time Range setting of Maximum. The second attribute will have a Formula Data Reference. In the second attribute( Formula) set a variable equal to the first attribute( PI Point), then make the equation equal to that variable. I’ve included images of both the Event Frame attributes and the Formula Configuration. In PI Vision display the second attribute with the Formula Data Reference. This method will allow you to display the attribute value of Maximum. It’s not elegant, but it works without the need for an additional PI Tag.