How do i get this to write to a txt file instead of message box pleaseWr

    Function ReceiveSerialData() As String
        ' Receive strings from a serial port. 
        Dim returnStr As String = ""

        Dim com1 As IO.Ports.SerialPort = Nothing
            com1 = My.Computer.Ports.OpenSerialPort("COM3")
            com1.ReadTimeout = 10000
                Dim Incoming As String = com1.ReadLine()
                If Incoming Is Nothing Then
                    Exit Do
                    returnStr &= Incoming & vbCrLf
                End If
        Catch ex As TimeoutException
            MessageBox.Show("Error: Serial Port read timed out.")
            If com1 IsNot Nothing Then com1.Close()
        End Try

        Return returnStr
    End Function

That doesnt really explain how to

No kidding. Microsoft would explain a beach by describing (in great detail) every grain of sand and every possible activity that can be done on that beach. Simple examples are often lacking.

Declare a StreamWriter as

Dim sw As New System.IO.StreamWriter("d:\temp\myfile.txt", False)

Set the second parameter to True to append to a file instead of overwriting. Replace






depending if you want to add a vbCrLf to the output. Don't forget to do


when done. You've only shown the code in the event handler and it would be inefficient to do the open/close repeatedly in the handler. You might want to do the open and close at a higher level.

Edited 1 Year Ago by Reverend Jim

Put this on top of your class or form1:
Imports System.IO
Put this into your function instead of the msgbox:

Using writer As StreamWriter = New StreamWriter("C:\append.txt", True)
            writer.WriteLine("First line appended; 1")
        End Using

This creates a new file if the file doesn't exist

That doesn't really explain how to

No offence but did you even scroll down and check out the examples? From there you would have seen how to write and read to and from text files.

It's great that you have been given examples but MSDN is your core documentation and if you are serious about learning to program I highly suggest you get familiar with it. It won't answer all of your questions but it will help with most.

Again, not trying to be rude just trying to point you in the right direction.

 My.Computer.FileSystem.WriteAllText('your text file name here', 'the return that you display as message here', True)

That should also work.

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