Private Sub cmdCRC_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdCRC.Click
 
        Dim varDaten As String = "010003GET" 'Datastring, contains destination 
        ' adress, sender adress, length and GET
        Dim varDatenByte(8) As Byte 'Array, used to save ASCI Byte values
        Dim varI As Integer 'used for counting
        Dim varJ As Integer 'used for counting
        Dim varBIT(8) As String 'Array, for saveing binary value for each ASCII 
        ' Byte value
        Dim varDatenPaket As String = "" 'Datastring, contains binary 
        ' translation of raw Data
        Dim varPoly As String = "1000000100001" 'Polynom x^16+x^12+x^5+1
        Dim varTeilwert As String 'Value divided by Polynom
        Dim varXOR As String = "" 'Result of XOR divison
        Dim varCRC As String 'Final CRC
 
        varDatenByte = System.Text.Encoding.ASCII.GetBytes(varDaten) 'write the 
        ' ASCII Byte value for each char of varDaten in a seperated 
        ' varDatenByte of the Array; from left to right
 
        For varI = 0 To 8 Step 1 'set each member of the varBIT array to "" ( _
          empty, no chars)
            varBIT(varI) = ""
        Next
 
        For varI = 0 To 8 Step 1 'For Next, increments the Counter
 
            For varJ = 7 To 0 Step -1 'For Next, decrements the second Counter
                'Divides each varDatenByte by 2^7 to 0, cuts everything after 
                ' decimalpoint and inserts the result on last place in string
                varBIT(varI) = varBIT(varI).Insert(varBIT(varI).Length, CType(( _
                  varDatenByte(varI) \ (2 ^ varJ)), String))
                'Divides each varDatenByte by 2^7 to 0, deletes the old value 
                ' of varDatenByte and sets it with the rest of division
                varDatenByte(varI) = (varDatenByte(varI) Mod (2 ^ varJ))
 
            Next
        Next
        'Finished Part 1, String into binary
        For varI = 8 To 0 Step -1  'Puts all values of varBit array in one 
        ' String --> varDatenPacket
            varDatenPaket = varDatenPaket.Insert(0, CType(varBIT(varI), String))
        Next
 
        varDatenPaket = varDatenPaket & "1111111111111111" 'puts FFFF Init 
        ' Value to the end of String
 
 
        Do Until varDatenPaket.Substring(0, 1) <> "0" 'Deletes leading Zero
            varDatenPaket = varDatenPaket.Remove(0, 1)
        Loop
 
        varTeilwert = varDatenPaket.Substring(0, 13) 'Puts first 14 Bits into 
        ' Memory
        varDatenPaket = varDatenPaket.Remove(0, 13) 'Cuts first 14 Bits from 
        ' Original Data
 
        Do Until varDatenPaket.Length = 0 'Does until all Bits are calculated
 
            varXOR = "" 'Init/Clear XOR
            For varI = 12 To 0 Step -1 'XOR for each of 16 Bits
                varXOR = varXOR.Insert(0, CType((varTeilwert.Substring(varI, 1) _
                  Xor varPoly.Substring(varI, 1)), String))
 
            Next
 
            Do Until varXOR.Substring(0, 1) <> "0" 'Deletes leading Zero
                varXOR = varXOR.Remove(0, 1)
            Loop
 
 
            Do Until varXOR.Length = 13 Or varDatenPaket.Length = 0
                varXOR = varXOR.Insert(varXOR.Length, varDatenPaket.Substring( _
                  0, 1)) 'Fills XOR with new Data
                varDatenPaket = varDatenPaket.Remove(0, 1) 'Removes moved Bits 
                ' from original Data
            Loop
 
            If varDatenPaket.Length = 0 Then 'Cancels DO UNTIL if Datastring 
            ' length is 0, expands XOR-Value to length 16
                Do Until varXOR.Length = 16
                    varXOR = varXOR.Insert(0, "0")
                Loop
                Exit Do
            End If
 
            varTeilwert = varXOR 'Result of XOR to new Data
        Loop
        varTeilwert = varXOR 'Result of XOR to new Data
        varXOR = "" 'Init/Clear XOR
        varPoly = "1111111111111111" 'Final XOR value sets to FFFF
 
        For varI = 15 To 0 Step -1 'Final XOR
            varXOR = varXOR.Insert(0, CType((varTeilwert.Substring(varI, 1) Xor _
              varPoly.Substring(varI, 1)), String))
        Next
 
 
        varCRC = varXOR 'Rest of XOR to CRC
 
        Me.lblCRC.Text = varCRC 'Shows CRC
 
    End Sub

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