
Re: PI performances equations
jru Jul 11, 2018 9:36 PM (in response to GDIMIRanim)1 of 1 people found this helpfulHi Ranim,
I apologize for the slow response rate. If you were able to find an appropriate solution for your use case, please feel free to let us know. In the meantime, here are some of my thoughts on the matter.
First of, based on the syntax of the formula you are using, it looks like you are trying to calculate the change in volumetric flow in the span of that minute. And you would like to totalize that measurement over the course of 1 day.
Based on the formulaic complexity of this calculation, I'd recommend that you create a PI Performance Equation Tag or PI Calculation with the following syntax: (TagVal('FlowRate','*')  TagVal('FlowRate','*1m'))*TagVal('Density','*')
Then you can use the Total data retrieval method with a calculation interval of 24 hours to get your desired result.
If you want to use a running total for the day, you'll need to use a PI Performance Equation so that you can historize the results of your volumetric change calculation to a PI Tag and use a Totalizer tag or another PI Performance Equation Tag or PI Calculation with the syntax: TagTot('VolumeChange','t','*') to get that result. Bear in mind that this requires you to use a PI Performance Equation tag for your volumetric change calculation as you are not able to reference a PI Calculation in another PI Calculation.
If I misunderstood your use case, please feel free to let me know what your end goal is.
~Jesse