UnityとArduinoをシリアル通信 ref: http://qiita.com/yjiro0403/items/54e9518b5624c0030531

file0.txt

Serial.print(Signal1);
Serial.print("\t");
Serial.print(Signal2);
Serial.print("\t");
...
Serial.print(Signaln);
Serial.println();

file1.txt

  if ( Serial.available() ) {
    char mode = Serial.read();
    switch (mode) {
      case '0' : digitalWrite(13, LOW);  break;
      case '1' : digitalWrite(13, HIGH); break;
    }
  }

file2.txt

using System.IO.Ports;
using System.Threading; //スレッド通信

file5.txt

serialPort_ = new SerialPort(portName,baudRate, Parity.None, 8, StopBits.One);

file6.txt

IOException: アクセスが拒否されました

hogehoge.cs

public class hogehoge : MonoBehaviour
{
  //先ほど作成したクラス
  public SerialHandler serialHandler;

  ...

  void Start()
  {
     //信号を受信したときに、そのメッセージの処理を行う
     serialHandler.OnDataReceived += OnDataReceived;
  }

  void Updata()
  {
    //文字列を送信
    serialHandler.Write("hogehoge");
  }

    //受信した信号(message)に対する処理
    void OnDataReceived(string message)
    {
        var data = message.Split(
                new string[]{"\t"}, System.StringSplitOptions.None);
        if (data.Length < 2) return;

        try {
           ...
        } catch (System.Exception e) {
            Debug.LogWarning(e.Message);
        }
    }
}

SerialHandler.cs

using UnityEngine;
using System.Collections;
using System.IO.Ports;
using System.Threading;

public class SerialHandler : MonoBehaviour
{
    public delegate void SerialDataReceivedEventHandler(string message);
    public event SerialDataReceivedEventHandler OnDataReceived;

    //ポート名
    //例
    //Linuxでは/dev/ttyUSB0
    //windowsではCOM1
    //Macでは/dev/tty.usbmodem1421など
    public string portName = "COM1";
    public int baudRate    = 9600;

    private SerialPort serialPort_;
    private Thread thread_;
    private bool isRunning_ = false;

    private string message_;
    private bool isNewMessageReceived_ = false;

    void Awake()
    {
        Open();
    }

    void Update()
    {
        if (isNewMessageReceived_) {
            OnDataReceived(message_);
        }
        isNewMessageReceived_ = false;
    }

    void OnDestroy()
    {
        Close();
    }

    private void Open()
    {
        serialPort_ = new SerialPort(portName, baudRate, Parity.None, 8, StopBits.One);
         //または
         //serialPort_ = new SerialPort(portName, baudRate);
        serialPort_.Open();

        isRunning_ = true;

        thread_ = new Thread(Read);
        thread_.Start();
    }

    private void Close()
    {
        isNewMessageReceived_ = false;
        isRunning_ = false;

        if (thread_ != null && thread_.IsAlive) {
            thread_.Join();
        }

        if (serialPort_ != null && serialPort_.IsOpen) {
            serialPort_.Close();
            serialPort_.Dispose();
        }
    }

    private void Read()
    {
        while (isRunning_ && serialPort_ != null && serialPort_.IsOpen) {
            try {
                message_ = serialPort_.ReadLine();
                isNewMessageReceived_ = true;
            } catch (System.Exception e) {
                Debug.LogWarning(e.Message);
            }
        }
    }

    public void Write(string message)
    {
        try {
            serialPort_.Write(message);
        } catch (System.Exception e) {
            Debug.LogWarning(e.Message);
        }
    }
}