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Imports System.IO.Ports
Imports System.Text

Public Class Form1

   Dim SerialPort1 As New System.IO.Ports.SerialPort()

   Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
       SerialPort1.PortName = "COM4"
       SerialPort1.BaudRate = 9600
       SerialPort1.Parity = Parity.None
       SerialPort1.StopBits = StopBits.One
       SerialPort1.DataBits = 8
       SerialPort1.Handshake = Handshake.RequestToSend
       SerialPort1.DtrEnable = True
       SerialPort1.RtsEnable = True
       SerialPort1.NewLine = vbCrLf

   End Sub

   Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
       Dim message As String = ConvertUTF8ToCUSD2(RichTextBox1.Text)
       SerialPort1.Open()
       If SerialPort1.IsOpen() Then
           SerialPort1.Write("AT" & vbCrLf)
           SerialPort1.Write("AT+CUSD=2" & vbCrLf)
           SerialPort1.Write("AT+CMGF=1" & vbCrLf)
           SerialPort1.Write("AT+CMGS=" & Chr(34) & TextBox1.Text & Chr(34) & vbCrLf)
           SerialPort1.Write(message & Chr(26))

           MsgBox("يتم الارسال")
       Else
           MsgBox("لم يتم")
       End If
   End Sub

   Public Function ConvertUTF8ToCUSD2(s As String) As String
       Dim code As String = String.Empty
       For Each c As Char In s.ToCharArray
           code &= AscW(c).ToString("X4")
       Next
       Return code
   End Function

End Class