Conectando nodejs a arduino mediante el puerto serie

gistfile1.js

//Ejemplo sencillo para poder manejar un motor servo conectado aun ardunio desde nodejs


//app.js fichero principal tipo express
var express = require('express');
//npm install serialport
//https://github.com/voodootikigod/node-serialport
var serialport = require("serialport");
var SerialPort = serialport.SerialPort; // localize object constructor
var app = module.exports = express.createServer();
// Configuration

app.configure(function(){
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(__dirname + '/public'));
});

app.configure('development', function(){
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

app.configure('production', function(){
  app.use(express.errorHandler());
});

// Routes
app.get('/', function(req, res){
  res.render('index', {
    title: 'Express'
  });
});

//hacemos get desde jquery /public/javascripts/aplicacion.js
app.get('/volumen/:id', function(req, res){
  console.log(req.params.id);
  var serial_port = new SerialPort("/dev/tty.usbserial-A4000PDf", {baudrate: 9600});
  serial_port.write(req.params.id);
  serial_port.close();
});

// Only listen on $ node app.js
if (!module.parent) {
  app.listen(3000);
  console.log("Express server listening on port %d", app.address().port);
}


//aplication.js cliente jquery
-- VISUAL LINE --
(function() {

$( "#slider-vertical" ).slider({
      orientation: "vertical",
      range: "min",
      min: 0,
      max: 180,
      value: 60,
      slide: function( event, ui ) {
        if(ui.value <=90){
          $.get("volumen/z");
        }else if(ui.value <=160){
          $.get("volumen/a");
        }
        $( "#amount" ).val( ui.value );
      }
    });
    $( "#amount" ).val( $( "#slider-vertical" ).slider( "value" ) );

})();

//layout.jade mirar documentación de express, pero añade cabecera y script
!!! 5
html
  head
    title= 'Calculador Consumo Co2'
    link(rel='stylesheet', href='/stylesheets/style.css')
    link(rel='stylesheet', href='/stylesheets/aristo/jquery-ui-1.8.5.custom.css')
    script(type='text/javascript', src='/javascripts/json.js')
    script(type='text/javascript', src='https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js')
    script(type='text/javascript', src='https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.7/jquery-ui.min.js')
    script(type='text/javascript', src='/javascripts/jquery.dataTables.js')
    script(type='text/javascript', src='/javascripts/jgcharts.js')
    body
      != body
    script(type='text/javascript', src='/javascripts/application.js')

//index.jade se accede cuando se hace una petición get a express
#demo
  label(for="amount")Volume
  input(type="text", id="amount", style="border:0; color:#f6931f; font-weight:bold;")
  #slider-vertical(style="height:200px;")
                                                                     
//#########################Arduino##########################
//Sección arduino 
#include <Servo.h>
#define LED 13 

Servo myservo;
int position = 0;

byte inbyte = 0;
boolean active = false;

void setup()
{
 myservo.attach(9);  // attaches the servo on pin 9 to the servo object
 pinMode(LED, OUTPUT); 
 Serial.begin(9600);
 Serial.println("servo attached");
 myservo.write(position);
 delay(1000);
}


void loop()
{ 
 inbyte = Serial.read(); //Read one byte (one character) from serial port. 
 if(inbyte == 'a'){
  position += 10;
  Serial.print("datos");
  Serial.println (position);
  int dato;
  dato = myservo.read();
  Serial.println(dato);
  myservo.write(position);
 }
 if(inbyte == 'z'){
  position -= 10;
  Serial.print("datos");
  Serial.println (position);
  int dato;
  dato = myservo.read();
  Serial.println(dato);
  myservo.write(position);
 }
}