Reading Arduino Pin

Hello, I’m working on a project but never used Processing before. I’m having some troubles in reading an Arduino pin state with Processing.
I have a LED connected to my PIN13, I opened StandardFirmata in Arduino and set my pin LED always HIGH. Then I wrote the following code in Processing:

import processing.serial.*;
import cc.arduino.*;
Arduino arduino;
int ledPin = 13;

void setup()
arduino = new Arduino(this, Arduino.list()[0], 57600);
arduino.pinMode(ledPin, Arduino.INPUT);

void draw()
  int b = arduino.digitalRead(ledPin);

but what I get in the screen is always 0. It looks Processing can’t read the actual state of my pin13. What should I do? I have searched a lot on internet but couldn’t find any help. I found another similar Topic here but the solutions proposed there didn’t solve my problem.

Thank you.