Zeroing a Vernier force probe
Not sure if this is what you mean, but:

const int FP = 0;  // force probe analog pin
const int OFFSET = 10; // your deadband depending on your sensors consistency too
int init_read = 0;  // initial read
int curr_read = 0;  // this will be constantly updated till zeroing is done

void setup(){
  Serial.begin(9600);
  //the rest of your setup()
}

void loop(){
  if (Serial.available() &amp;&amp; (Serial.read() == 'z')){  // if you sent anything with the monitor and if 'z' is present   
    init_read = analogRead(FP); // initial read from sensor before 'zeroing' begins 
    while (abs(curr_read - init_read) &lt; OFFSET){ // here you indicate the condition that would mean the probe has been zeroed
      // make your adjustments or whatever
      curr_read = analogRead(FP);  // take a new reading and check in the next iteration
    }
    Serial.print("Zeroing is done.");
  }
}


z is the command you send from the serial monitor to begin zeroing.