Help - Millis Function

[DaveX]

If you think of the on/off solenoids as LEDs, there's:

Flashing multiple LEDs at the same time

C style code My code below flashes 2 LEDs, one connected to pin 2 and one to Pin 3, each with a suitable resistor (220 Ohms or thereabouts) to 0V. Each LED flashes independently of the other. Notes I have used separate functions called from the loop function to illustrate putting code into functions rather than trying to do everything in the loop function. There are 2 different flash functions, each uses millis() independently for timing. The first, flashEqualOnOffPin2(), flashes the LED on …

...but as written, your problem is simpler. It could be done with delays.