Exception Thrown - Receive data from Arduino to Visual Basic - vb.net

Question

I'm trying to send serial data from Arduino and read it on Visual Basic. When I execute the code sometimes works and sometimes doesn't: throwing exception, System.ArgumentOutOfRangeException: 'Index and length must refer to a location within the string. Can you help me?
I'm new to Visual Basic, thanks.
Imports System.IO
Imports System.IO.Ports
Imports System.Threading
Public Class Form1
Dim TWSL, TWAL, THL, AoAL, WAL, PeL, RoilL, RyL, RydL As Integer
Dim TWS, TWA, TH, AoA, WA, Pe, Roil, Ry, Ryd, TWSResult, TWAResult, THResult, AoAResult, WAResult, PeResult, RoilResult, RyResult, RydResult As String
Dim StrSerialIn, StrSerialInRam As String
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Me.CenterToParent()
SerialPort1.PortName = "COM4"
SerialPort1.BaudRate = 9600
SerialPort1.Open()
Timer1.Start()
SerialPort1.Write(TrackBarAWA.Value & Chr(10))
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Try
StrSerialIn = SerialPort1.ReadExisting
Dim TB As New TextBox
TB.Multiline = True
TB.Text = StrSerialIn
If TB.Lines.Count > 0 Then
If TB.Lines(0) = "Failed to read" Then
Timer1.Stop()
SerialPort1.Close()
Return
End If
StrSerialInRam = TB.Lines(0).Substring(0, 2)
If StrSerialInRam = "A" Then
TWS = TB.Lines(0)
TWSL = TWS.Length
Else
TWS = TWS
End If
StrSerialInRam = TB.Lines(1).Substring(0, 3)
If StrSerialInRam = "B" Then
TWA = TB.Lines(1)
TWAL = TWA.Length
Else
TWA = TWA
End If
StrSerialInRam = TB.Lines(2).Substring(0, 3)
If StrSerialInRam = "C" Then
TH = TB.Lines(2)
THL = TH.Length
Else
TH = TH
End If
StrSerialInRam = TB.Lines(3).Substring(0, 2)
If StrSerialInRam = "D" Then
AoA = TB.Lines(3)
AoAL = AoA.Length
Else
AoA = AoA
End If
StrSerialInRam = TB.Lines(4).Substring(0, 1)
If StrSerialInRam = "E" Then
WA = TB.Lines(4)
WAL = WA.Length
Else
WA = WA
End If
StrSerialInRam = TB.Lines(5).Substring(0, 3)
If StrSerialInRam = "F" Then
Pe = TB.Lines(5)
PeL = Pe.Length
Else
Pe = Pe
End If
StrSerialInRam = TB.Lines(6).Substring(0, 3)
If StrSerialInRam = "G" Then
Roil = TB.Lines(6)
RoilL = Roil.Length
Else
Roil = Roil
End If
StrSerialInRam = TB.Lines(7).Substring(0, 3)
If StrSerialInRam = "H" Then
Ry = TB.Lines(7)
RyL = Ry.Length
Else
Ry = Ry
End If
StrSerialInRam = TB.Lines(8).Substring(0, 3)
If StrSerialInRam = "I" Then
Ryd = TB.Lines(8)
RydL = Ryd.Length
Else
Ryd = Ryd
End If
TWSResult = Mid(TWS, 2, TWSL)
TWAResult = Mid(TWA, 2, TWAL)
THResult = Mid(TH, 2, THL)
AoAResult = Mid(AoA, 2, AoAL)
WAResult = Mid(WA, 2, WAL)
PeResult = Mid(Pe, 2, PeL)
RoilResult = Mid(Roil, 2, RoilL)
RyResult = Mid(Ry, 2, RyL)
RydResult = Mid(Ryd, 2, RydL)
TWSvalue.Text = TWSResult
TWAvalue.Text = TWAResult
THvalue.Text = THResult
AoAvalue.Text = AoAResult
WAvalue.Text = WAResult
PeValue.Text = PeResult
RoilValue.Text = RoilResult
RyValue.Text = RyResult
RydValue.Text = RydResult

Answer 1

From what I gather, you are trying to get characters from specific places in specific lines on a text box. Based on the error message you included in your question, I assume the error occurs on a line of code containing the "String. Substring" method. If the string where you are getting the substring from is too short to cover the range you have specified in the substring method, you will get this error. For instance, if you are getting a substring that's 3 characters long from line 2 starting at character 0 and it has less than 3 characters, you will get this error.
See the documentation on the String.Substring method here