B4R Question AT commands

Sub Command_Transmit_By_Lora(CMDType As String ,ID As String,Msg As String)
    Dim Command As String
    Dim Totalmsg As String
    Totalmsg=JoinStrings(Array As String(CMDType,",",ID,",",Msg,",",100))
    Command=JoinStrings(Array As String("AT+SEND=100",",",Totalmsg.Length,",",Totalmsg,CRLF))
    SerialNative2.WriteBytes(Command,0,Command.Length)
    Log("send lora tx=",Command)
    Timer1.Enabled=True
End Sub