int signalPin = 2;
int value = 0 ,status = 0;
void setup() {
  // put your setup code here, to run once:
  pinMode(signalPin , INPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  status = digitalRead(signalPin);
  value += digitalRead(signalPin) ? 1 : -1;
  Serial.print("status :");
  Serial.print(status);
  Serial.print(",\t");
  Serial.print("value :\t");
  Serial.println(value);
  delay(100);
}