Question Serial Port Communication (Ports dont show up)

andicom

New member
Joined
Aug 14, 2012
Messages
2
Programming Experience
Beginner
Hi guys, first of all I'm not very good at programming and I've tried to be as explanatory as possible in my codes. I've been trying to write a program which enables a user to chat (recieved & transmit) messages via Serial Port using a simple custom made IR modem. I've constructed the modem and now trying to write my own simple program instead of using Terminal or other already written program (i.e. Tera Term). Btw, I'm on Windows 7 and using the Microsoft Visual Express 2010 Environment

I've written the codes below, based on the tutorial at this site.
Tutorial Site

as well as this microsoft website for reference (putting it here just in case)
MSDN Serial Port Class reference

Problem (as of now)
The combo boxes cmbComPort doesn't seem to catch any available ports on my computer. I suspected that probably there is none! So I checked and here is what I found. Based on this, I assume there is a Serial Port on my computer and hence this is not the source of the problem (Let me know otherwise, because I'm not really sure). I run the debug and an error message popped out. I then build the program to test it out. Both error messages are attached below

Questions
1. Are my codes somewhere wrong? or is it my computer? Please show which part is the error
2. Is there anyway to beutify the codes? (make it shorter, simpler, that would be nice)
3. This is a project which accepts any extra features (writing my own program is definitely one of it). I could appreciate if you guys can drop any ideas on the features, whether related to the serial port communication or the program interface itself. I can think of a few, such as Save Chats to file, Load Chat files, Help/Tutorial file - all are to be implemented once I figured the above error. Moreover, I was thinking is there anyway I can draw a 'bubble chat' to display the conversations instead of plain rich text box? that would be nice.

Thanks in advance! :D
Error Messages and Project files

CODES:


VB.NET:
'Chatty Raffy Version 1.3
'This is a simple program to demonstrate Serial Ports communication via a simple custom made IR Modem. 

Imports System
Imports System.ComponentModel
Imports System.Threading
Imports System.IO.Ports

Public Class frmMain

    Dim myPort As Array  'an array to store list of available ports

    Delegate Sub SetTextCallback(ByVal [text] As String) 'Added to prevent threading errors during receiveing of data

    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)

        'Fill up the cmbBaudRate Combo box to common baud rates used
        cmbBaudRate.Items.Add(9600)
        cmbBaudRate.Items.Add(19200)
        cmbBaudRate.Items.Add(38400)
        cmbBaudRate.Items.Add(57600)
        cmbBaudRate.Items.Add(115200)

        'procedure to detect all available ports and store them in the myPort array
        For Each port_name As String In IO.Ports.SerialPort.GetPortNames
            Dim myPort As New IO.Ports.SerialPort(port_name)
            If myPort.IsOpen = True Then
                cmbComPort.Items.Add(port_name)
            End If
        Next

        'initiate the combo boxes
        cmbComPort.SelectedIndex = 0  'set cmbComPort text to the first COM port detected
        cmbBaudRate.SelectedIndex = 0    'set cmbBaudRate text to the first Baud rate on the list
        cmbParity.SelectedIndex = 0    'set cmbParity text to the first Baud rate on the list
        cmbStopBit.SelectedIndex = 0    'set cmbStopBit text to the first Baud rate on the list

        'btnDisconnect.Enabled = False   'disable the disconnect button

    End Sub

    'open the selected serial port and start the connection
    Private Sub btnConnect_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnect.Click
        SerialPort1.PortName = cmbComPort.Text      'set Serial Port to the selected COM port 
        SerialPort1.BaudRate = cmbBaudRate.Text      'set Baud rate to the selected value Baud rate
        SerialPort1.Parity = cmbParity.Text     'set parity setting to the selected value 
        SerialPort1.StopBits = cmbStopBit.Text  'set stop bit setting to the selected value

        SerialPort1.DataBits = 8    'use the default 8 bit for data bit length

        SerialPort1.Open()      'open the chosen serial port

        btnConnect.Enabled = False      'disable the Connect button
        btnDisconnect.Enabled = True    'enable the Disconnect button
        picboxDisconnect.Visible = False 'disable the disconnect picture
        picboxConnect.Visible = True 'enable the disconnect picture
    End Sub


    'close the serial port currently in used, hence closing the connection
    Private Sub btnDisconnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisconnect.Click
        SerialPort1.Close()     'close the used Serial Port

        btnConnect.Enabled = True  'esable the Connect button
        btnDisconnect.Enabled = False  'disable the Disconnect button
        picboxDisconnect.Visible = True 'enable the 'disconnect' picture
        picboxConnect.Visible = False 'disable the 'connect' picture
    End Sub

    'send the text contained in the txtText to the serial port in ASCII using the 'SEND' key
    Private Sub btnSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        SerialPort1.Write(txtTransmit.Text & vbCr)
    End Sub


    'detect data at the serial port and call ReceivedText automatically 
    Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs)
        ReceivedText(SerialPort1.ReadExisting())
    End Sub


    'read incoming messages at serial port once data is detected
    Private Sub ReceivedText(ByVal [text] As String)
        'compare the ID of the Creating Thread to the ID of the Calling Thread
        If Me.rtbReceived.InvokeRequired Then
            Dim x As New SetTextCallback(AddressOf ReceivedText)
            Me.Invoke(x, New Object() {(text)})
        Else
            Me.rtbReceived.Text &= [text]
        End If
    End Sub



    'this section prevents user from making any changes to the current connection without disconnecting

    Private Sub cmbComPort_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
        If SerialPort1.IsOpen = False Then
            SerialPort1.PortName = cmbComPort.Text
        Else
            'pop an error message if user try to change port without closing the current port in use
            MsgBox("Please close the currently used port before making any changes to the connection setting", vbCritical)
        End If
    End Sub


    Private Sub cmbBaudRate_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbBaudRate.SelectedIndexChanged
        If SerialPort1.IsOpen = False Then
            SerialPort1.BaudRate = cmbBaudRate.Text
        Else
            'pop an error message if user try to change Baud rate without closing the current port in use
            MsgBox("Please close the currently used port before making any changes to the connection setting", vbCritical)
        End If
    End Sub

    Private Sub cmbParity_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbBaudRate.SelectedIndexChanged
        If SerialPort1.IsOpen = False Then
            SerialPort1.Parity = cmbParity.Text
        Else
            'pop an error message if user try to change Baud rate without closing the current port in use
            MsgBox("Please close the currently used port before making any changes to the connection setting", vbCritical)
        End If
    End Sub

    Private Sub cmbStopBit_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbBaudRate.SelectedIndexChanged
        If SerialPort1.IsOpen = False Then
            SerialPort1.StopBits = cmbStopBit.Text
        Else
            'pop an error message if user try to change Baud rate without closing the current port in use
            MsgBox("Please close the currently used port before making any changes to the connection setting", vbCritical)
        End If
    End Sub



End Class
 

JohnH

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Dim myPort As New IO.Ports.SerialPort(port_name)
If myPort.IsOpen = True Then
Creating a SerialPort object does not open it, documentation for the constructor would have explained so if it did, so IsOpen will always be False in this code.
About there being ports in computer or not, put a breakpoint in your GetPortNames loop, is any results returned?
 
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