delay()

Pauses the program for the amount of time (in miliseconds) specified as parameter (there are 1000 milliseconds in a second). During this amount of time, all Z-Wave specific tasks continue to execute, Z-Wave.Me bootloader continue to poll the service button and the USB. Only the user sketch is frozen. Due to strict radio timeouts, it is forbidden to call this function in the Z-Wave callback functions (getters and setters of Z-Wave channels). The Z-Wave.Me bootloader will ignore delay() in this situation. Please use a flag instead: set a boolean variable in getters/setters that will be checked in loop() function. delay(ms) ms the number of milliseconds to pause none
void setup() {
  pinMode(20, OUTPUT);          // sets the digital pin as output
}

void loop() {
  digitalWrite(20, HIGH);       // sets the LED on
  delay(1000);                  // waits for a second
  digitalWrite(20, LOW);        // sets the LED off
  delay(1000);                  // waits for a second
}