SerialPortManager class

SerialPortManager is a singleton class I wrote to be used in some .NET projects that need to communicate using serial data communication protocol. It’s basically a simple wrapper to System.IO.Ports.SerialPort class. I would use this class when I develop a .NET app that needs to communicate mostly with Arduino board. So, I would like to share the code here, so hopefully it would benefit to others.

SerialPortManager class source code

File name: SerialPortManager.cs // Mirror link: Gist

using System;
using System.IO;
using System.IO.Ports;
using System.Threading;

namespace HeiswayiNrird.Singleton
{
    public sealed class SerialPortManager
    {
        private static readonly Lazy<SerialPortManager> lazy = new Lazy<SerialPortManager>(() => new SerialPortManager());
        public static SerialPortManager Instance { get { return lazy.Value; } }

        private SerialPort _serialPort;
        private Thread _readThread;
        private volatile bool _keepReading;

        private SerialPortManager()
        {
            _serialPort = new SerialPort();
            _readThread = null;
            _keepReading = false;
        }

        /// <summary>
        /// Update the serial port status to the event subscriber
        /// </summary>
        public event EventHandler<string> OnStatusChanged;

        /// <summary>
        /// Update received data from the serial port to the event subscriber
        /// </summary>
        public event EventHandler<string> OnDataReceived;

        /// <summary>
        /// Update TRUE/FALSE for the serial port connection to the event subscriber
        /// </summary>
        public event EventHandler<bool> OnSerialPortOpened;

        /// <summary>
        /// Return TRUE if the serial port is currently connected
        /// </summary>
        public bool IsOpen { get { return _serialPort.IsOpen; } }

        /// <summary>
        /// Open the serial port connection using basic serial port settings
        /// </summary>
        /// <param name="portname">COM1 / COM3 / COM4 / etc.</param>
        /// <param name="baudrate">0 / 100 / 300 / 600 / 1200 / 2400 / 4800 / 9600 / 14400 / 19200 / 38400 / 56000 / 57600 / 115200 / 128000 / 256000</param>
        /// <param name="parity">None / Odd / Even / Mark / Space</param>
        /// <param name="databits">5 / 6 / 7 / 8</param>
        /// <param name="stopbits">None / One / Two / OnePointFive</param>
        /// <param name="handshake">None / XOnXOff / RequestToSend / RequestToSendXOnXOff</param>
        public void Open(
            string portname = "COM1",
            int baudrate = 9600,
            Parity parity = Parity.None,
            int databits = 8,
            StopBits stopbits = StopBits.One,
            Handshake handshake = Handshake.None)
        {
            Close();

            try
            {
                _serialPort.PortName = portname;
                _serialPort.BaudRate = baudrate;
                _serialPort.Parity = parity;
                _serialPort.DataBits = databits;
                _serialPort.StopBits = stopbits;
                _serialPort.Handshake = handshake;

                _serialPort.ReadTimeout = 50;
                _serialPort.WriteTimeout = 50;

                _serialPort.Open();
                StartReading();
            }
            catch (IOException)
            {
                if (OnStatusChanged != null)
                    OnStatusChanged(this, string.Format("{0} does not exist.", portname));
            }
            catch (UnauthorizedAccessException)
            {
                if (OnStatusChanged != null)
                    OnStatusChanged(this, string.Format("{0} already in use.", portname));
            }
            catch (Exception ex)
            {
                if (OnStatusChanged != null)
                    OnStatusChanged(this, "Error: " + ex.Message);
            }

            if (_serialPort.IsOpen)
            {
                string sb = StopBits.None.ToString().Substring(0, 1);
                switch (_serialPort.StopBits)
                {
                    case StopBits.One:
                        sb = "1"; break;
                    case StopBits.OnePointFive:
                        sb = "1.5"; break;
                    case StopBits.Two:
                        sb = "2"; break;
                    default:
                        break;
                }

                string p = _serialPort.Parity.ToString().Substring(0, 1);
                string hs = _serialPort.Handshake == Handshake.None ? "No Handshake" : _serialPort.Handshake.ToString();

                if (OnStatusChanged != null)
                    OnStatusChanged(this, string.Format(
                    "Connected to {0}: {1} bps, {2}{3}{4}, {5}.",
                    _serialPort.PortName,
                    _serialPort.BaudRate,
                    _serialPort.DataBits,
                    p,
                    sb,
                    hs));

                if (OnSerialPortOpened != null)
                    OnSerialPortOpened(this, true);
            }
            else
            {
                if (OnStatusChanged != null)
                    OnStatusChanged(this, string.Format(
                    "{0} already in use.",
                    portname));

                if (OnSerialPortOpened != null)
                    OnSerialPortOpened(this, false);
            }
        }

        /// <summary>
        /// Close the serial port connection
        /// </summary>
        public void Close()
        {
            StopReading();
            _serialPort.Close();

            if (OnStatusChanged != null)
                OnStatusChanged(this, "Connection closed.");

            if (OnSerialPortOpened != null)
                OnSerialPortOpened(this, false);
        }

        /// <summary>
        /// Send/write string to the serial port
        /// </summary>
        /// <param name="message"></param>
        public void SendString(string message)
        {
            if (_serialPort.IsOpen)
            {
                try
                {
                    _serialPort.Write(message);

                    if (OnStatusChanged != null)
                        OnStatusChanged(this, string.Format(
                        "Message sent: {0}",
                        message));
                }
                catch (Exception ex)
                {
                    if (OnStatusChanged != null)
                        OnStatusChanged(this, string.Format(
                            "Failed to send string: {0}",
                            ex.Message));
                }
            }
        }

        private void StartReading()
        {
            if (!_keepReading)
            {
                _keepReading = true;
                _readThread = new Thread(ReadPort);
                _readThread.Start();
            }
        }

        private void StopReading()
        {
            if (_keepReading)
            {
                _keepReading = false;
                _readThread.Join();
                _readThread = null;
            }
        }

        private void ReadPort()
        {
            while (_keepReading)
            {
                if (_serialPort.IsOpen)
                {
                    //byte[] readBuffer = new byte[_serialPort.ReadBufferSize + 1];
                    try
                    {
                        //int count = _serialPort.Read(readBuffer, 0, _serialPort.ReadBufferSize);
                        //string data = Encoding.ASCII.GetString(readBuffer, 0, count);
                        string data = _serialPort.ReadLine();

                        if (OnDataReceived != null)
                            OnDataReceived(this, data);
                    }
                    catch (TimeoutException) { }
                }
                else
                {
                    TimeSpan waitTime = new TimeSpan(0, 0, 0, 0, 50);
                    Thread.Sleep(waitTime);
                }
            }
        }
    }
}

How to use

To retrieve the data, just subscribe to OnDataReceived event.

Example:

using HeiswayiNrird.Singleton;
using System.Windows;

namespace SerialPortSingleton
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        // Constructor
        public MainWindow()
        {
            InitializeComponent();

            // Subscribe to the event
            SerialPortManager.Instance.OnDataReceived += Handler_OnDataReceived;
        }

        // Event handler
        private void Handler_OnDataReceived(object sender, string incomingData)
        {
            // TODO
            // Process the data from 'incomingData' variable...
        }
    }
}

For something simpler, you may use anonymous function and marshall it to the main UI thread.

Example:

using HeiswayiNrird.Singleton;
using System;
using System.Windows;

namespace SerialPortSingleton
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        // Constructor
        public MainWindow()
        {
            InitializeComponent();

            // Subscribe to the event
            SerialPortManager.Instance.OnDataReceived += (sender, incomingData) =>
            {
                // TODO
                // Process the data from 'incomingData' variable...
                double value = Convert.ToDouble(incomingData); // Assuming incomingData contains "123"

                // Update to UI...
                Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                {
                    BindingTextBoxValue = value;
                }));
            };
        }

        // Binding properties
        public double BindingTextBoxValue { get; set; }
    }
}

To handle opening or closing the serial port connection, you may just call Open() or Close() method.

Example:

// To open/start serial port on COM4 with 9600 bps
SerialPortManager.Instance.Open("COM4", 9600);

// To close/stop serial port on COM4
SerialPortManager.Instance.Close();

SerialPortManager also provides a public event to be subscribe for receiving any status update/response. To get the status message, just subscribe to OnStatusChanged event or OnSerialPortOpened event for getting Boolean return either the serial port is opened or closed.

Example:

using HeiswayiNrird.Singleton;
using System.Windows;

namespace SerialPortSingleton
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        // Constructor
        public MainWindow()
        {
            InitializeComponent();

            // Subscribe to the event
            SerialPortManager.Instance.OnStatusChanged += (sender, status) =>
            {
                // Update connection status message to UI
                ConnectionStatus = status;
            };
        }

        // Binding properties
        public string ConnectionStatus { get; set; }
    }
}

How this class avoids the deadlock issue

SerialPortManager class uses ReadPort() method to be run on a new different thread and implements while loop statement for acquiring or reading data from the serial port. When SerialPortManager.Instance.Close() method is called, _keepReading variable will be set to false which will stop the app UI from receiving and updating the data while waiting the thread is fully terminated.

Using System.IO.Ports.SerialPort.Close() method directly on the app UI thread to stop acquiring/reading data will cause a deadlock issue or hand the application. This is because the serial port base stream is locked while serial port events are handled.