[RESOLVED] Serial Port Read Index Out Of Range Exception

[pourkascheff]

Well, Hello. It's me again.
Consider a half-duplex modbus RTU serial communication between two devices which we want to only listen. A repeater.
Without any CRC/Checksum complexity, I stuck at the beginning. What is the best approach to do such thing?

Here's the code so far but making 2 bytes to an integer applies for first 8 bytes and then an exception will occur for line #30 which is comparing it is a HoldingRegister or not (Correct received package). I mean using Try/Catch will do the matter for first 8 bytes and continues the loop. I need the whole data. Any clues is precious. Thanks in advanced.

Public Class Form1
 
    Private Buffer As Byte()    'I'M NOT SURE IT IS THE BEST WAY TO DECLARE A BYTE ARRAY WITH UNKNOWN/CHANGABLE LENGTH OR NOT
    
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Control.CheckForIllegalCrossThreadCalls = False 'FOR ERRORS FROM NOWHERE(?)
        Try
            If SerialPort1.IsOpen = False Then
            SerialPort1.Open()
            End If
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Critical)
            Application.Exit()
        End Try
    End Sub
 
    Private Sub SerialPort1_DataReceived(sender As Object, e As IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        If BackgroundWorker1.IsBusy = False Then
            BackgroundWorker1.RunWorkerAsync()  'IT'S GOING TO BE A VERY CROWDY CODE. LET THE BACKGROUNDWORKER DO THE LOOP THING FOR ME
        End If
    End Sub
    
    Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        Dim byteCount = SerialPort1.BytesToRead 'GET INPUT BUFFER SIZE
        If SerialPort1.BytesToRead > 8 Then 'IGNORE BLANK AND NOT REQUEST COMMANDS (GET ONLY ANSWERS FROM SLAVES. REQUEST COMMANDS ARE 8 BYTES)
            buffer = New Byte(byteCount) {}     'EXTEND VARIABLE/ARRAY AS IT IS
            SerialPort1.Read(Buffer, 0, byteCount)  'READ SERIAL PORT FUNCTION
            Dim UserControl as UserControl() = {UserControl1, UserControl2, UserControl3, UserControl4, UserControl5, UserControl6, UserControl7, UserControl8, UserControl9, UserControl10, UserControl11, UserControl12, UserControl13, UserControl14}    'THERE ARE 14 USERCONTROLS WHICH SORTING VALUES IN THEM IS REQUIRED
            
            If Buffer(1) = 3 And Buffer(2) = 192 Then 'CORRECT PACKET(S) INCOMING
            
                If Buffer(0) = 2 Then   'FIRST PARAMETER               
                    For i = 0 To 29 Step 2  'ARRANGING/ASSIGNING VALUES IN THEIR PLACES FOR 14 USERCONTROLS
                    UserControl(i/2).TextBox1.Text = (Val(Buffer(i+3)*256) + Val(Buffer(i+4))   'COMBINE 2 BYTES => INTEGER
                    Next                
                End If
                
                'If Buffer(0) = 3 Then  'SECOND PARAMETR
                ''SAME AS ABOVE
                'End If
                '.
                '.
                '.
                'If Buffer(0) = n Then  'LAST PARAMETR
                ''SAME AS ABOVE
                'End If
            End If
    'POSSIBLE 'BUFFER' DISPOSE/CLEAR CODE GOES HERE WHICH I DON'T KNOW HOW TO DO IT
        End If
    End Sub 
End Class

Exception full message:
IndexOutOfRangeException was unhandled by user code: Index was outside the bounds of the array.