How to display received data on Serial port - vb.net

Question

I am new to using Visual Basic and just have started coding using the language.
From simple coding, I want to try something a bit complex such as sending and receiving data through a serial port communication. I was able to go through a lot of tutorials about it and came about trying this code:
Imports System
Imports System.Threading
Imports System.IO.Ports
Imports System.ComponentModel
Public Class Form1
Dim myPort As Array
Delegate Sub SetTextCallback(ByVal [text] As String) 'Added to prevent threading errors during receiving of data
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
myPort = IO.Ports.SerialPort.GetPortNames()
ComboBox1.Items.AddRange(myPort)
Button2.Enabled = False
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
SerialPort1.PortName = ComboBox1.Text
SerialPort1.BaudRate = ComboBox2.Text
SerialPort1.Open()
Button1.Enabled = False
Button2.Enabled = True
Button3.Enabled = True
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
SerialPort1.Write(RichTextBox1.Text & vbCr) 'concatenate with \n
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
SerialPort1.Close()
Button1.Enabled = True
Button2.Enabled = False
Button3.Enabled = False
End Sub
Private Sub ReceivedText(ByVal [text] As String) 'input from ReadExisting
If Me.RichTextBox2.InvokeRequired Then
Dim x As New SetTextCallback(AddressOf ReceivedText)
Me.Invoke(x, New Object() {(text)})
Else
Me.RichTextBox2.Text &= [text] 'append text
End If
End Sub
Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
ReceivedText(SerialPort1.ReadExisting())
End Sub
End Class
Button1 is designated for Opening the Port while Button2 and Button3 are used to Write and Close the port respectively. The RichTextBox1 is where I can write the data I want to send and the RichTextBox2 is where the data received is displayed. Now my problem is whenever I click the button to Write data on the port nothing displays. I want to ask help on how to get about with this.

Answer 1

You can't write a message and read it on the same end of the serial communication.
If you want to "fake" the serial communication, so that your pc talks to itself, you have 2 solutions:
Use some nullmodem emulator to virtually create COM ports pairs that are connected through software. Software like com0com, does just what you are looking for, but sometimes is a bit tricky makings thingks work well at the start.
Another solution is to have 2 serial ports in your pc (with an usb
adapter for example) and connect the TRx pin of the sending port to the RDx pin
of the reading port, and the RDx pin of the sending port to the TRx pin
of the reading port. All other pins just 1 to 1. Then you can also read from write from one port and read from the other.
Both approaches do the same, the first through software, the second physically.
Here you have another SO question about that, where you can get more info. Also google "faking Serial ports" should help.