Expression Tag/Backfilling

Ignition
,
1

I want to do metric with multiple tags and therefore I created expression tags. Works fine and writing to history works perfect too.

How can i calculate these metrics backwards and save them to the historian?

Expression tag configuration: {[~]machine1/energy_input}/{[~]machine1/production}

This gives me energy efficiency at the moment. By writing the result back to the historian I can always look at the trend. Both tags ({[~]machine1/energy_input},…) were stored into the historian for several years and the expression tag is new.

How can I tell ignition to calculate the expression tag for several years in the past?

2

Please give an example of your inputs and the outputs you want. It's not clear from your question. (You can edit the original post with the pencil icon.)