Arduino stepper controll

#include <Stepper.h>

// Å tevilo korakov za 360 stopinjski obrat
#define KOB 200

//priklop motorja 1
#define MX1 32
#define MX2 33
#define MX3 34
#define MX4 35

//priklop motorja 2
#define MY1 40
#define MY2 41
#define MY3 42
#define MY4 43

//priklop motorja 3
#define MZ1 36
#define MZ2 37
#define MZ3 38
#define MZ4 39

Stepper motorX(KOB, MX1, MX2, MX3, MX4);
Stepper motorY(KOB, MY1, MY2, MY3, MY4);
Stepper motorZ(KOB, MZ1, MZ2, MZ3, MZ4);

//trenutna pozicija po korakih
int kX = 0;
int kY = 0;
int kZ = 0;
String koX;
String koY;
String koZ;

void setup() {
  Serial.begin(9600);

  //dolocanje hitrosti motorjev
  motorX.setSpeed(30);
  motorY.setSpeed(30);
  motorZ.setSpeed(30);
}

void loop() {
  if (Serial.available())
    {
        String data = Serial.readStringUntil(';');
        //X,koraki;
        //Y,koraki;
        //Z,koraki;
        //REF;

    String cmd = "";
    String koraki = "";



      int c = true;
      for (int i = 0; i < 16; i++)
        {
          if (data[i] == ';') return;
          if (c)
            {
              if (data[i] != ',') cmd += data[i];
              else c = false;
            }
          else if (data[i] != ',') koraki += data[i];

        }


        if (cmd == "X")
          {
            motorX.step(koraki.toInt());
            kX += koraki.toInt();

            Serial.println("Ukaz: "+cmd+" Koraki: "+koraki);
            printData();
          }
        else if (cmd == "Y")
          {
            motorY.step(koraki.toInt());
            kY += koraki.toInt();

            Serial.println("Ukaz: "+cmd+" Koraki: "+koraki);
            printData();
          }
        else if (cmd == "Z")
          {
            motorZ.step(koraki.toInt());
            kZ += koraki.toInt();

            Serial.println("Ukaz: "+cmd+" Koraki: "+koraki);
            printData();
          }
        else if (cmd == "REF")
          {
            motorX.step(-kX);
            motorZ.step(-kZ);
            motorY.step(-kY);

            kX = 0;
            kY = 0;
            kZ = 0;

            printData();
          }
      }
}
void printData()
  {
            koX = kX;
            koY = kY;
            koZ = kZ;

            Serial.println("X: "+koX+ " Y: "+koY+" Z: "+koZ);
  }