Arduino and visual basic Serial data 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
You've opened the port before you've configured it.