Difference between current and preceding row, filtered

[Angelo_M]

Hello everyone, 

I have this problem to solve.

I have to calculate the duration of engine running with this data:

The dataset contains more events then only these two, so i have to filter to consider only this two events.
I was thinking to create a table with pivot data with columns SERIAL | DATE ON | DATE OFF | DURATION ENGINE ON

But i'm new in Power Query/Dax and i don't know how i can do.

Someone have suggestions? Thanks you!

[Rupak_bi]

try this