Convert hexadecimal to ascii VB.NET

Public Function HexToStr(ByVal Data As String) As String
        Dim com As String = ""
        For x = 0 To Data.Length - 1 Step 2
            com &= ChrW(CInt("&H" & Data.Substring(x, 2)))
        Next
        Return com
    End Function

    

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim st As String = TextBox1.Text
        Dim com As String
        Dim a As Integer = 0
        Dim b As Integer
        Dim c As String = ""
        ' while loop execution '

        b = TextBox1.Text.Count

        While a < b
            c = TextBox1.Text.Substring(0 + a, 2)
            com = HexToStr(c).ToString
            RichTextBox1.Text = RichTextBox1.Text & com
            a = a + 2
        End While
    End Sub