GSM INTERFACE
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There are many different kinds of
applications SMS applications in the market today, and many others are being
developed. Applications in which SMS messaging can be utilized are virtually unlimited.
Some common examples of these are given below:
- Person-to-person
text messaging is the most commonly used SMS application, and it is what
the SMS technology was originally designed for.
- Many
content providers make use of SMS text messages to send information such
as news, weather report, and financial data to their subscribers.
- SMS
messages can carry binary data, and so SMS can be used as the transport
medium of wireless downloads. Objects such as ringtones, wallpapers,
pictures, and operator logos can be encoded in SMS messages.
- SMS
is a very suitable technology for delivering alerts and notifications of
important events.
- SMS
messaging can be used as a marketing tool.
In general, there are two ways to send SMS
messages from a computer / PC to a mobile phone:
- Connect
a mobile phone or GSM/GPRS modem to a computer / PC. Then use the computer
/ PC and AT commands to instruct the mobile phone or GSM/GPRS modem to
send SMS messages.
- Connect
the computer / PC to the SMS center (SMSC) or SMS gateway of a wireless
carrier or SMS service provider. Then send SMS messages using a protocol /
interface supported by the SMSC or SMS gateway
AT Commands
AT commands are instructions used to control a modem. AT is the
abbreviation of ATtention. Every command line starts with "AT" or
"at". That's why modem commands are called AT commands. There are two
types of AT commands:
1. Basic commands are AT
commands that do not start with a "+". For example, D (Dial), A
(Answer), H (Hook control), and O (Return to online data state) are the basic
commands.
2. Extended commands are AT
commands that start with a "+". All GSM AT commands are extended
commands. For example, +CMGS (Send SMS message), +CMGL (List SMS messages), and
+CMGR (Read SMS messages) are extended commands.
The FORM DESIGN as show below, Here we using combo box for
port selection and textbox for entering
mobile number to send sms,and message field to type message and send button.
The complete code as given below, Here we have
to create two class 1)sms ,2)program
The class sms will set all pre-requirements in
order to send sms,and port values and program class will load the forms and
this will initiate the application.
Imports System.Data.SqlClient
Imports System.Net.Sockets
Imports System.Text
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
If SerialPort1.IsOpen Then
SerialPort1.Close()
End If
Try
With SerialPort1
.PortName = "COM11"
.BaudRate = 9600
.Parity = IO.Ports.Parity.None
.DataBits = 8
.StopBits = IO.Ports.StopBits.One
.Handshake = IO.Ports.Handshake.None
.NewLine = vbCrLf
.RtsEnable = True
.RtsEnable = True
End With
SerialPort1.Open()
SerialPort1.WriteLine("at+cmgf=1" &
vbCrLf)
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim
Num as Integer
Dim
Msg as String
Num=TexBox1.text
Msg=TexBox2.text
Send_sms(Num,Msg)
End
Sub
Sub send_sms(ByVal Cont_no As String, ByVal acc_details As String)
Dim Mobile = Cont_no
Dim message = acc_details
SerialPort1.WriteLine("at+cmgd=1" &
vbCrLf)
Sleep(1000)
Dim a As String
a = "at+cmgs=""+91" & Mobile & """"
SerialPort1.WriteLine(a & vbCrLf)
Sleep(1000)
SerialPort1.WriteLine(message &
Chr(26))
End Sub
End
Class
