Serial Communication Port will get Closed after clicking on Close button in C#

Question

I am working on project in C# windows form application.

In this project main Form contain subform for communication of serial port. SubForm "Connect" have two buttons Connect and Close. Also 5 comboboxes to select baudrate, Com name,parity, stopbits and databits.

When I click on Connect button after selecting all settings from comboboxes. port gets connected and connect button becomes Disconnect. And I will close the Connect form

Now my problem is that when I reopen the form, without clicking on Disconnect button when i Close the form , the Comport will disconnected. I don't want that ComPort close.

Please help me to solve this bug. I don't know where I did mistake. Thanks in advance.

Connect Class Code

 public partial class Connect : Form
{
    public bool Connect_Status = false;

    public Connect()
    {
        InitializeComponent();
        COM_List();

    }

   private void COM_List()
    {
        for (int i = 0; i < CommPortManager.Instance.GetCommList().Count; i++)
        {
            cb_CommPort.Items.Add(CommPortManager.Instance.GetCommList()[i]);
        }
    }


   private void btn_Connect_Click(object sender, EventArgs e)
   {
       if (btn_Connect.Text == "Connect")
       {
           CommPortManager.Instance.PortName = cb_CommPort.Text;
           CommPortManager.Instance.BaudRate = cb_BaudRate.Text;
           CommPortManager.Instance.Parity = cb_Parity.Text;
           CommPortManager.Instance.StopBits = cb_StopBits.Text;
           CommPortManager.Instance.DataBits = cb_DataBits.Text;

           if ((cb_CommPort.Text == "") || (cb_BaudRate.Text == "") || (cb_Parity.Text == "") || (cb_DataBits.Text == "") || (cb_StopBits.Text == ""))
           {
               if (cb_CommPort.Text == "")
               {
                   MessageBox.Show("Please select COM Port and then Connect", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
               }
               else if (cb_BaudRate.Text == "")
               {
                   MessageBox.Show("Please select BaudRate and then Connect", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
               }
               else if (cb_Parity.Text == "")
               {
                   MessageBox.Show("Please select Parity and then Connect", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
               }
               else if (cb_DataBits.Text == "")
               {
                   MessageBox.Show("Please select DataBits and then Connect", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
               }
               else if(cb_StopBits.Text == "")
               {
                   MessageBox.Show("Please select StopBits and then Connect", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
               }

               Connect_Status = false;
           }
           else
           {
               if (CommPortManager.Instance.COM_Open() == false)
               {
                   MessageBox.Show("Could not open the COM port. Most likely it is already in use, has been removed, or is unavailable.", "TestCertificate", MessageBoxButtons.OK, MessageBoxIcon.Information);
                   Connect_Status = false;
               }
               else
               {
                   //CommPortManager.Instance.COM_Close();
                   Connect_Status = true;
                   btn_Connect.Text = "Disconnect";
                   cb_CommPort.Enabled = false;
                   cb_BaudRate.Enabled = false;
                   cb_DataBits.Enabled = false;
                   cb_Parity.Enabled = false;
                   cb_StopBits.Enabled = false;
                   btn_Connect.BackColor = System.Drawing.Color.Salmon;
               }

           }
       }
       else
       {
           CommPortManager.Instance.COM_Close();
           btn_Connect.Text = "Connect";
           Connect_Status = false;
           cb_CommPort.Enabled = true;
           cb_BaudRate.Enabled = true;
           cb_DataBits.Enabled = true;
           cb_Parity.Enabled = true;
           cb_StopBits.Enabled = true;
           btn_Connect.BackColor = System.Drawing.Color.DarkTurquoise;
       }
   }

   private void btn_Close_Click(object sender, EventArgs e)
   {
       this.Close();
   }

 private void Connect_Load(object sender, EventArgs e)
 {
      //code here to setup the value;
     cb_CommPort.Text = CommPortManager.Instance.PortName;
     cb_BaudRate.Text = CommPortManager.Instance.BaudRate;
     cb_Parity.Text = CommPortManager.Instance.Parity;
     cb_StopBits.Text = CommPortManager.Instance.StopBits;
     cb_DataBits.Text = CommPortManager.Instance.DataBits;

     if (CommPortManager.Instance.IsOpen == true)
     {
         btn_Connect.Text = "Disconnect";
         btn_Connect.BackColor = System.Drawing.Color.Salmon;
         cb_CommPort.Enabled = false;
         cb_BaudRate.Enabled = false;
         cb_DataBits.Enabled = false;
         cb_Parity.Enabled = false;
         cb_StopBits.Enabled = false;
     }
     else
     {
         btn_Connect.Text = "Connect";
         Connect_Status = false;
         cb_CommPort.Enabled = true;
         cb_BaudRate.Enabled = true;
         cb_DataBits.Enabled = true;
         cb_Parity.Enabled = true;
         cb_StopBits.Enabled = true;
         btn_Connect.BackColor = System.Drawing.Color.DarkTurquoise;

     }
 }


}

Answer 1

I suspect that the form load event. you need to set the connection status true when its open

    private void Connect_Load(object sender, EventArgs e)
    {
        //code here to setup the value;
        cb_CommPort.Text = CommPortManager.Instance.PortName;
        cb_BaudRate.Text = CommPortManager.Instance.BaudRate;
        cb_Parity.Text = CommPortManager.Instance.Parity;
        cb_StopBits.Text = CommPortManager.Instance.StopBits;
        cb_DataBits.Text = CommPortManager.Instance.DataBits;

        if (CommPortManager.Instance.IsOpen == true)
        {
            Connect_Status = true;
            btn_Connect.Text = "Disconnect";
            btn_Connect.BackColor = System.Drawing.Color.Salmon;
            cb_CommPort.Enabled = false;
            cb_BaudRate.Enabled = false;
            cb_DataBits.Enabled = false;
            cb_Parity.Enabled = false;
            cb_StopBits.Enabled = false;
        }
        else
        {
            btn_Connect.Text = "Connect";
            Connect_Status = false;
            cb_CommPort.Enabled = true;
            cb_BaudRate.Enabled = true;
            cb_DataBits.Enabled = true;
            cb_Parity.Enabled = true;
            cb_StopBits.Enabled = true;
            btn_Connect.BackColor = System.Drawing.Color.DarkTurquoise;

        }
    }

Answer 2

It looks like that if you press Connect it changes your btn_Connect.Text to Disconnect (if the port is open) now the button text is "Disconnect" and if (btn_Connect.Text == "Connect") is now false and the else is called which does CommPortManager.Instance.COM_Close();