Using SUMFILTERED with the Machine Activity Table

I’m trying to create an operator compliance analytic that shows a machine uptime ratio like utilization, but where both segments are in the “uptime” state which shows the ratio of running with and without an operator logged into the machine.

If the station app is being used we write the current operator to the MAT so it should be as simple as using SUMFILTERED based on whether the field is populated or not. I have the following simplified expression (I’ll turn it into % later) which Tulip considers valid, but no results are returned (empty graph):

sumfiltered(texttonumber(@Uptime Duration ), len(totext(@Operator )) != 0)