Question

I am using serial port communications in my ASP.NET webform application:

private bool sendSMS(int portNo, string mobNo, string details)
{
    try
    {
        SerialPort SerialPort1 = new SerialPort();
        SerialPort1.PortName = "COM" + portNo.ToString();
        SerialPort1.BaudRate = 9600;
        SerialPort1.Parity = Parity.None;
        SerialPort1.DataBits = 8;
        SerialPort1.StopBits = StopBits.One;
        SerialPort1.RtsEnable = true;
        SerialPort1.DtrEnable = true;
        SerialPort1.Encoding.GetEncoder();
        SerialPort1.ReceivedBytesThreshold = 1;
        SerialPort1.NewLine = Environment.NewLine;
        SerialPort1.Open();
        SerialPort1.Write("AT" + SerialPort1.NewLine);
        Sleep(500);
        SerialPort1.Write("AT+CMGF=1" + SerialPort1.NewLine);
        Sleep(500);
        SerialPort1.Write("AT+CMGS=" + (char)34 + mobNo + (char)34 +
                                    SerialPort1.NewLine);
        Sleep(1000);
        SerialPort1.Write(details + (char)26);
        Sleep(2000);
        SerialPort1.Close();
    }
    catch
    {

    }
    return true;
}

This method works when I send in a single message… But when I want to send SMSes in bulk opening and closing port everytime is not a good idea… Is it possible to use a serial port like session in c#?

When I open a port I want it to be open for one hour and then if my time expires I want to close the port and open it the next time… Is it possible?

Answer 1

You could create an object and in its constructor/initialization call SerialPort.Open() and implement IDisposable to call SerialPort.Close(). For the lifetime of the object, it’ll be open.

Something a little more detailed is below (though definitely not a complete solution). The general idea is to encapsulate the port connection lifetime into the object lifetime so that when the object goes out of scope/use and gets cleaned by the GC then so does the port connection.

@jrista makes a good point about needing to handle any error conditions. ErrorReceived will help with that, as well as ol’ fashioned error handling throughout this code where necessary.

public class SerialPortConnection : IDisposable
{
    private bool disposed;
    public SerialPort Port { get; protected set; }

    public SerialPortConnection(int portNo)
    {
        this.Initialize(portNo);
        this.Port.ErrorReceived += this.portError;
        this.Port.Open();
    }

    public void Initialize(int portNo)
    {
        this.Port = new SerialPort();
        this.Port.PortName = "COM" + portNo.ToString();
        /* snip */
        this.Port.Encoding.GetEncoder();
        this.Port.ReceivedBytesThreshold = 1;
        this.Port.NewLine = Environment.NewLine;
    }

    protected void portError(
        object sender,
        SerialErrorReceivedEventHandler args)
    {
        // Do whatever with the error, maybe need to reopen the socket.
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!disposed)
        {
            if (disposing)
            {
                this.Port.Close();
                this.Port.Dispose(disposing);
            }
            this.disposed = true;
        }
    }

    public void Dispose()
    {
        this.Dispose(true);
    }
}