int state = 0; int flag = 0; ////////////////////RELAYS int relay1 = 8; int relay2 = 9; int relay3 = 10; int relay4 = 11; int staterelay1 = LOW; int staterelay2 = LOW; int staterelay3 = LOW; int staterelay4 = LOW; ; void setup() { pinMode(relay1, OUTPUT); pinMode(relay2, OUTPUT); pinMode(relay3, OUTPUT); pinMode(relay4, OUTPUT); Serial.begin(9600); } void loop() { if(Serial.available() > 0){ state = Serial.read(); flag=0; } ///////////////////////////RELAY 1 if (state == '0') { digitalWrite(relay1, LOW); if(flag == 0){ flag = 1; } } else if (state == '1') { digitalWrite(relay1, HIGH); if(flag == 0){ flag = 1; } } //////////////////////////RELAY 2 if (state == '2') { digitalWrite(relay2, LOW); if(flag == 0){ flag = 1; } } else if (state == '3') { digitalWrite(relay2, HIGH); if(flag == 0){ flag = 1; } } /////////////////////////RELAY 3 if (state == '4') { digitalWrite(relay3, LOW); if(flag == 0){ flag = 1; } } else if (state == '5') { digitalWrite(relay3, HIGH); if(flag == 0){ flag = 1; } } //////////////////RELAY 4 if (state == '6') { digitalWrite(relay4, LOW); if(flag == 0){ flag = 1; } } else if (state == '7') { digitalWrite(relay4, HIGH); if(flag == 0){ flag = 1; } } }