Hello A.J, There are lots of ways to do this: One approach would be to use a 1min timer. When the timer completes, lower the valve and start the timer again. (Timers like TON, TOF, OUT_T, etc.) Another approach would be to use PLC's internal system clock (SD214 - depending on PLC) and lower the valve when the value changes. Which PLC are you working with and what language are you programming in (ladder, FBD, ST)?