Arduino + U-MC 2100-WA Motor Controller Code

int PWM_OUT = 9;
float duty = 0.0;
int onTime;
void setup()
{
  pinMode(PWM_OUT, OUTPUT);
  pinMode(13, OUTPUT);
}

void loop()
{
  onTime = floor(duty*50);
  digitalWrite(PWM_OUT, HIGH);
  digitalWrite(13, HIGH);
  delay(onTime);
  digitalWrite(PWM_OUT,LOW);
  digitalWrite(13, LOW);
  delay(50-onTime);
}