   pinMode(pingPin3, INPUT);
   duration = pulseIn(pingPin3, HIGH);
   cm3 = microsecondsToCentimeters(duration);
-  
+ 
+ /* 
   // probe sensor 4
   pinMode(pingPin4, OUTPUT);
   digitalWrite(pingPin4, LOW);


void loop()
{
  // check for measurement request on UART
  if (Serial.available() > 0) {
    // read the incoming byte:

  Serial.print(cm2);
  Serial.print(":");
  Serial.print(cm3);  
  //Serial.print(":");
  //Serial.print(cm4);
  Serial.println();  
}

