const byte dipPins[] = {9, 8, 7, 6, 5, 4, 3, 2};

void writeByte(const byte b) {
  for (int8_t i = 7; i >= 0; i--) Serial.write(bitRead(b, i) + '0');
  Serial.println();
  // here we actually print a human readable version of the byte
  // for binary communicatoin it shoud be
  // Serial.write(b);
}

void setup() {
  Serial.begin(115200);
  for (byte aPin : dipPins) pinMode(aPin, INPUT_PULLUP);
}

void loop() {
  static byte oldValue = 0x42;

  byte currentValue = 0;

  for (byte aPin : dipPins) {
    currentValue <<= 1;
    currentValue |= (digitalRead(aPin) == HIGH) ? 0 : 1; // INPUT_PULLUP => inverse input
  }

  if (currentValue != oldValue) {
    writeByte(currentValue);
    oldValue = currentValue;
  }
}