A proof of concept experiment. A switch is triggered and the state is read by the computer which selects the appropriate action, in this case a relay will be fired. It sends a signal to the relay board which then opens or closes the relay, providing 5v power to a LED light.
It was critical to show that I could read the state of a switch and immediately act on it, by either opening or closing a relay (which could be connected to a light, or a solenoid, or some other cool things that we will talk about later).
This is the basis of everything else that we are building on. And it worked perfectly.