int in = 0;                   // Variable to store the desired value
int pinOutLed = 9;  
int pwm = 0;
void setup() {                // This executes once
  Serial.begin(9600);             // Initialize serial port
  pinMode(pinOutLed, OUTPUT);        // Prepare output pin
}

void loop() {                 // This loops continuously
  while(Serial.available() > 0){         // Check if there's data
   
    in = Serial.read();           // Read said data into the variable "in"
    if (in == '+'){
      if(pwm < 256){
        pwm = pwm + 10;
      }
      
      analogWrite(pinOutLed, pwm);
   }
   else if(in == '-'){
      if(pwm > -1){
        pwm = pwm - 10;
      }
      analogWrite(pinOutLed, pwm);
   }
  }
     

}