I have been asked to come up with an equation that will return a value from the previous two months. I've created a calculation called 'Monthly' that calculates the monthly average flow. I need to be able to return the monthly average for last month and the month before that separately. So, since its currently October, I need the monthly average for September and August.
I'm successfully returning the monthly average for last month by using PrevVal('Monthly',bom('*')) in PI Analytics and I'm not historizing it as a tag.
I've tried a few things but can't seem to return the monthly average flow for 2 months prior.