But why would the valve stay on for instance when the 'True' case becomes false?
Because in the FALSE state a different valve is controlled, atleast you named those boolean buttons "Main valve" and "Bypass valve"…
Sorry what is a DO value?
DO = digital output. It's a common abbreviation, similar to AI, AO, and DI…
Any ideas how to make it work this way or is it scrap?
Use a state machine…
