user904: I am trying to send command serially through Vb.through serial monitor working fine . But Through VB it not detecting port
My arduino code:
int ledPin = 2; // the number of the LED pin

void setup() {
Serial.begin(9600); // set serial speed
pinMode(ledPin, OUTPUT); // set LED as output
digitalWrite(ledPin, LOW); //turn off LED
}


void loop(){
while (Serial.available() == 0); // do nothing if nothing sent
int val = Serial.read() - '0'; // deduct ascii value of '0' to find numeric value of sent number

if (val == 1) { // test for command 1 then turn on LED
Serial.println("LED on");
digitalWrite(ledPin, HIGH); // turn on LED
}
else if (val == 0) // test for command 0 then turn off LED
{
Serial.println("LED OFF");
digitalWrite(ledPin, LOW); // turn off LED
}
else // if not one of above command, do nothing
{
//val = val;
Serial.println("Wrong command");
}
Serial.println(val);
Serial.flush(); // clear serial port
}

VB Code
Imports System.IO
Imports System.IO.Ports
Imports System.Threading

Public Class Form1
    Shared _continue As Boolean


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        SerialPort1.Open()
        SerialPort1.PortName = "COM3"

        SerialPort1.BaudRate = 9600
        SerialPort1.DataBits = 8
        SerialPort1.Parity = IO.Ports.Parity.None
        SerialPort1.StopBits = IO.Ports.StopBits.One
        SerialPort1.Handshake = IO.Ports.Handshake.None
        SerialPort1.Encoding = System.Text.Encoding.Default 'very important!

    End Sub


    Private Sub Button1_Click_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1_Click.Click
        SerialPort1.Open()
        SerialPort1.Write("1")
        SerialPort1.Close()
    End Sub



    Private Sub Button2_Click_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2_Click.Click
        SerialPort1.Open()
        SerialPort1.Write("0")
        SerialPort1.Close()
    End Sub


End Class

Error I am getting .Arduino port is 3. and configured to port 3 . i dont know why it giving error.
The port 'com10' does not exist.

This Line added as you said
Private Sub Current_Read_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        SerialPort1.Open()
        Dim str As String
        str = SerialPort1.ReadExisting
        Current_Read.Text = str
        SerialPort1.Close()
    End Sub

This is working But data not being updating
Private Sub Current_Read_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Current_Read.Text =SerialPort1.ReadLine
    End Sub


user368: You've opened the port before you've configured it.

904: <p>I am trying to send command serially through Vb.through serial monitor working fine . But Through VB it not detecting port
<strong>My arduino code:</strong></p>

<pre><code>int ledPin = 2; // the number of the LED pin

void setup() {
Serial.begin(9600); // set serial speed
pinMode(ledPin, OUTPUT); // set LED as output
digitalWrite(ledPin, LOW); //turn off LED
}


void loop(){
while (Serial.available() == 0); // do nothing if nothing sent
int val = Serial.read() - '0'; // deduct ascii value of '0' to find numeric value of sent number

if (val == 1) { // test for command 1 then turn on LED
Serial.println("LED on");
digitalWrite(ledPin, HIGH); // turn on LED
}
else if (val == 0) // test for command 0 then turn off LED
{
Serial.println("LED OFF");
digitalWrite(ledPin, LOW); // turn off LED
}
else // if not one of above command, do nothing
{
//val = val;
Serial.println("Wrong command");
}
Serial.println(val);
Serial.flush(); // clear serial port
}
</code></pre>

<p>VB Code</p>

<pre><code>Imports System.IO
Imports System.IO.Ports
Imports System.Threading

Public Class Form1
    Shared _continue As Boolean


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        SerialPort1.Open()
        SerialPort1.PortName = "COM3"

        SerialPort1.BaudRate = 9600
        SerialPort1.DataBits = 8
        SerialPort1.Parity = IO.Ports.Parity.None
        SerialPort1.StopBits = IO.Ports.StopBits.One
        SerialPort1.Handshake = IO.Ports.Handshake.None
        SerialPort1.Encoding = System.Text.Encoding.Default 'very important!

    End Sub


    Private Sub Button1_Click_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1_Click.Click
        SerialPort1.Open()
        SerialPort1.Write("1")
        SerialPort1.Close()
    End Sub



    Private Sub Button2_Click_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2_Click.Click
        SerialPort1.Open()
        SerialPort1.Write("0")
        SerialPort1.Close()
    End Sub


End Class
</code></pre>

<p>Error I am getting .Arduino port is 3. and configured to port 3 . i dont know why it giving error.</p>

<pre><code>The port 'com10' does not exist.
</code></pre>

<p>This Line added as you said</p>

<pre><code>Private Sub Current_Read_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        SerialPort1.Open()
        Dim str As String
        str = SerialPort1.ReadExisting
        Current_Read.Text = str
        SerialPort1.Close()
    End Sub
</code></pre>

<p>This is working But data not being updating</p>

<pre><code>Private Sub Current_Read_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Current_Read.Text =SerialPort1.ReadLine
    End Sub
</code></pre>
 368: <p>You've opened the port before you've configured it.</p>
