Serial communication

[InduGokul]

i want to perform serial communication on selecting

.Net Framework2.0--->Visual Basic--->Device application

presently i am using this code

Imports System.IO.Ports
Imports System.IO.Ports.Serialport

If Button1.Text Is "open port" then
    SerialPort1.Open()
    Button1.Text="close port"
    Button2.Enabled=True

Else If Button1.Text Is "close port" then
    SerialPort1.Close()
    Button1.Text="open port"
    Button2.Enabled=False
End If

//Inside button2 i am writing this code
SerialPort1.WriteLine(Textbox1.Text)
Listbox1.Items.Add("sent:" +TextBox1.Text)

//Inside serialport's property in DataReceived,i hav written this statement
ListBox1.Items.Add("Received" +Serialport1.ReadLine())

but i am getting error as

"An unhandled exception of type System.InvalidO perationExcepti on occurred in System.dll
Additional Information: The basestream is only available when the port is open "

so plz anyone help me in this issue ...

Thanking U in advance.....
expecting ur valuable results earlier.....

Regards
Indu

[tlhintoq]

Additional Information: The basestream is only available when the port is open "

When you are sending the text to the port, the port is not open.
Just because you issued a command to open the port you cannot assume that it worked. Maybe there is a problem with the port. Maybe the port number you specified is not valid. Maybe some other application or the OS closed the port after you opened it. Maybe your attempt to opent he port failed because you didn't specify everything correctly that you needed to.

Coding is easy in a perfect world. Too bad we don't live in one. I have found that for every line of code there are 10 more to handle probable error conditions.

Where you open the port

If Button1.Text Is "open port" then
    SerialPort1.Open()
    Button1.Text="close port"
    Button2.Enabled=True

You never check to see if it really opened. You just assume it did and activate your send button.

In your send method, do you check if the port is open before you try to shove text through it?