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


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

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