I have an ignition project setup where I am trending the value of a water meter over time. Every thirty minutes, the register value of the meter is stored. I am trying to figure out a way to use this data to show the usage for given periods.
I created an easy chart and can view the reading at the meter over time. However, I cannot seem to figure out how to display the amount of water used for a given hour; only the value of the meter at the start of the hour and the end of the hour.
I tried creating a pen that took the maximum value in a period and one the took the minimum value in a period. I then created a calculated pen that took the difference. However, every time I tried this, I got a null exception error from java.
Does anyone have a suggestion on how to do this? Thanks