Leitura com comparação

int rele = 2;
int rele2 = 3;
int rele3 = 4;
int rele4 = 5;
int rele5 = 6;
int rele6 = 7;
int rele7 = 8;
int rele8 = 9;
int estant = 0;
int estant2 = 0;
int estant3 = 0;
int estant4 = 0;
int estant5 = 0;
int estant6 = 0;
int estant7 = 0;
int estant8 = 0;

void setup() {
  pinMode(rele,  INPUT_PULLUP);//BOMBA1
  pinMode(rele2, INPUT_PULLUP);//BOMBA2
  pinMode(rele3, INPUT_PULLUP);//DEFEITO BOBMA1
  pinMode(rele4, INPUT_PULLUP);//DEFEITO BOMBA2
  pinMode(rele5, INPUT_PULLUP);//FALTA DE AGUA NA CAIXA SUPERIOR
  pinMode(rele6, INPUT_PULLUP);//FALTA DE AGUA NA CAIXA INFERIOR
  pinMode(rele7, INPUT_PULLUP);//PAINEL LIGADO OU DESLIGADO
  pinMode(rele8, INPUT_PULLUP);//INDEFINIDO
  Serial.begin(9600);
}
void loop() {

int relest  = digitalRead(rele);
int relest2 = digitalRead(rele2);
int relest3 = digitalRead(rele3);
int relest4 = digitalRead(rele4);
int relest5 = digitalRead(rele5);
int relest6 = digitalRead(rele6);
int relest7 = digitalRead(rele7);
int relest8 = digitalRead(rele8);

  if (estant == relest) { //BOMBA 1
  }
  else {
    if (relest == LOW) {
      Serial.print(">");
      Serial.println("B1 ON ");
    }
    else {
      Serial.print("<");
      Serial.println("B1 OFF ");
    }
    estant = relest;
  }

delay(1);

  if (estant2 == relest2) { //BOMBA 2
  }
  else {
    if (relest2 == LOW) {
      Serial.print("(");
      Serial.println("B2 ON ");
    }
    else {
      Serial.print(")");
      Serial.println("B2 OFF ");
    }
      estant2 = relest2;
  }

  delay(1);

  if (estant3 == relest3) { //DEFEITO B1
  }
  else {
    if (relest3 == LOW) {
      Serial.print("*");
      Serial.println("DF B1 ");
    }
    else {
      Serial.print("+");
      Serial.println("DF B1 OFF ");
    }
      estant3 = relest3;
  }

  delay(1);

  if (estant4 == relest4) { //DEFEITO B2
  }
  else {
    if (relest4 == LOW) {
      Serial.print("-");
      Serial.println("DF B2 ");
    }
    else {
      Serial.print("_");
      Serial.println("DF B2 OFF ");
    }
      estant4 = relest4;
  }

  delay(1);

  if (estant5 == relest5) { //FALTA DE AGUA CAIXA SUPERIOR
  }
  else {
    if (relest5 == LOW) {
      Serial.print("!");
      Serial.println("FA.RES.SUP ");
    }
    else {
      Serial.print("#");
      Serial.println("ABS.RES.SUP ");
    }
    estant5 = relest5;
  }

  delay(1);

  if (estant6 == relest6) { //FALTA DE AGUA NA CAIXA INFERIOR
  }
  else {
    if (relest6 == LOW) {
      Serial.print("[");
      Serial.println("FA.RES.INF(SBP) ");
    }
    else {
      Serial.print("]");
      Serial.println("RES.CHEIO ");

    }
     estant6 = relest6;
  }

  delay(1);

  if (estant8 == relest8) { //PAINEL ONOFF
  }
  else {
    if (relest8 == LOW) {
      Serial.print("{");
      Serial.println("PAINEL ON ");
    }
    else {
      Serial.print("}");
      Serial.println("PAINEL OFF ");
    }
      estant8 = relest8;
  }

  delay(3000);
}