/*Node1*/ int id=1; //needed for adressing the board int incoming = 0; void setup() { // Begin the Serial at 9600 Baud Serial.begin(9600); Serial.setTimeout(10); pinMode(LED_BUILTIN, OUTPUT); } void loop() { // check if data is available if (Serial.available() > 0) { // read the incoming data incoming = Serial.parseInt(); // say what you got for debugging Serial.print("I received: "); Serial.println(incoming); Serial.println(id * 1 + 1); Serial.println(id * 1); } // check if incoming data is for the right node // if so and data ends with '1' turn LED ON, when data ends with '0' turn LED OFF if (incoming == id * 10 + 1) { // turn LED on: digitalWrite(LED_BUILTIN, HIGH); } else if (incoming == id * 10){ // turn LED off: digitalWrite(LED_BUILTIN, LOW); } }