Simulink resets arduino

Question

I am working on servo motors control through serial communication protocol, I am sending data from Simulink to arduino and vice versa, The problem I am getting is that once I open Simulink Servo motors start turning while no command is sent or received from both, I tought that Simulink is initializing (reseting) arduino, so I decided to add a capacitor between Gnd & reset (I also tried with a resistor between 5v & reset), It actually works when I try to use Arduino IDE, Arduino is not reseting, but When i use it with Simulink it doesn't make change, Servo motors still turning randomly (I think that when I start or close simulation, Servo Are going to their initial position, I am not sure). I tried to add initial Position in Setup() function but in vain, It doesn't make sens! I tried using different arduino cards (MEGA, ESP32...Etc.) but in vain.

Does anyone have an idea about how to figure out this problem? Here is Simulink control code : & Arduino code :

#include <SCServo.h>
SCSCL sc;
//Estructura Union
typedef union {
  float number;
  uint8_t bytes[4];
} valor;
valor velocidad;
unsigned long timeold;
int vel = 0;
float value;
void setup() {
Serial1.begin(1000000);
  sc.pSerial = &Serial1;
  Serial.begin(9600);
}
void loop() {
  //Pregunta si tenemos un dato a recibir
  if (Serial.available() > 0) {
    value = recepcion();
  }
//Transforma el valor del voltaje (0-5) a velocidad
  vel = map(value, 0, 5, 0, 1023);
  //Activa el motor dirección Backward con la velocidad
  sc.WritePos(3,  value, 0);
velocidad.number = sc.ReadPos(3);
Serial.write('V');
  for (int i = 0; i < 4; i++) {
    Serial.write(velocidad.bytes[i]);
  }
  Serial.write('\n');
  delay(50);
}
//Recibir Flotante
float recepcion() {
  int i;
  valor buf;
  for (i = 0; i < 4; i++)
    buf.bytes[i] = Serial.read();
  return buf.number;
}
//Función para la lectura del encoder

Thank you !