Using Cayenne for remote projects

Projects General Guidance
4

Just read the state of the button (digitalRead() typically) and react to that in your loop(). To block it from doing anything else something like:

while (digitalRead(buttonPin) == LOW) {
  ditigalWrite(solenoidPin, HIGH);
}
digitalWrite(solenoidPin, LOW);

This assuming button is wired active LOW, and the solenoid active HIGH.

Replace that later by something that reads your Cayenne.

You'll have to come up with a better solution for your 500 meter gap. Both Bluetooth and WiFi can't do this. Considering the distance you may need something with fixed directional antennas.