SMS Via USB Serial Port

rodmcleay · December 21st, 2005, 02:33 AM

Hi all,
I am currently creating an app to send sms message to GSM Modem (mobile phone) using System.IO.Ports.SerialPort.
I beleive I have correctly configured the port as I am able to send AT commands to the modem and get replies form the modem which tells me I am connected.
But my problem is using the AT commands themselves, I dont know if they are being sent as expected.
All the commands I am using work with Hyperterminal on the same GSM Modem/Phone.

The problem may be the escape character for the end of the message, in Hyperterminal it is CTRL+Z, which I have read is chr(26).

Or it could be the other AT commands themselves.

Can anyone see my error in this code:

Code:

private void OpenPort()
        {            
            port.PortName = "COM4";
            port.ReceivedBytesThreshold = 1;
            port.BaudRate = 115200;
            port.DtrEnable = true;
            port.DataReceived += new SerialDataReceivedEventHandler(OnCom4Receive); 
            port.Open();
        }
        private void SendMSG()
        {
            port.WriteLine("AT");
            port.WriteLine("AT+CMGF=1");
            port.WriteLine("AT+CMGS=\"0403075???\"");
            //port.WriteLine("> TESTING 1,2,3,4" + char.ConvertFromUtf32(26));
            port.WriteLine("TESTING 1,2,3,4" + Convert.ToChar(26));
        }
        static private void OnCom4Receive(object sender, SerialDataReceivedEventArgs e)
        {
            MessageBox.Show(port.ReadExisting());            
        }

There are not any errors returned at all.
Many thanks for your time in reading this.

======================================
They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad.
======================================

rodmcleay · December 21st, 2005, 05:30 AM

Fixed the problem, need to explicitly send carriage return and line feed
            port.WriteLine("AT\r");
            port.WriteLine("AT+CMGF=1\r");
            port.WriteLine("AT+CMGS=\"0403075???\"\r");
            //port.WriteLine("> TESTING 1,2,3,4" + char.ConvertFromUtf32(26));
            port.WriteLine("TEST" + '\x001a');
            //port.Write('\x001a'.ToString());

======================================
They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad.
======================================

snramkumar · February 28th, 2006, 02:02 PM

Very much happy to see the C# code to send SMS to GSM Modem using System.IO.Ports.SerialPort

We have a requirement to read all the received SMS from GSM Modem, need your help.

rsrika · March 8th, 2006, 03:28 AM

Hey

i am constantly getting a Security exception when i am trying at Port.Open(). Can you help ?

can u send me this sample application for sending this SMS using AT Command.

Thanks

rodmcleay · March 8th, 2006, 03:39 AM

Sorry rsika,
I never came across a secutiy exception.
The code in my first entry above with the amendments in the second will consitiute an application if you call the methods on a button click.
Accessing Ports is a security concern so you may need to have admin privilages or the like.
Are you an admin on the machine you are using?

======================================
They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad.
======================================

rsrika · March 8th, 2006, 04:40 AM

Hi Rodam,

This is cool !! i was able to solve the security problem ..but still i am not able to send the SMS

I am able to do it via Hyperterminal though :-(

rodmcleay · March 8th, 2006, 05:47 AM

Can you post the code you are using to send.

======================================
They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad.
======================================

rsrika · March 8th, 2006, 06:14 AM

private void OpenPort()
        {

            port.PortName = "COM6";
            port.ReceivedBytesThreshold = 1;

            port.DtrEnable = true;
          // port.DataReceived += new SerialDataReceivedEventHandler(OnCom4Receive);
            if (!port.IsOpen)
                port.Open();
            else
            {
                port.Close();
                port.Open();
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OpenPort();
            port.WriteLine("AT\r");
            port.WriteLine("AT+CMGF=1\r");
            string str = "AT+CMGS=\\" + textBox1.Text + "\\" + "\\r";
            port.WriteLine(str);
            port.WriteLine("TEST" + '\x001a');
        }

These are the code..i even tried hardcoding the number ...

rsrika · March 8th, 2006, 06:15 AM

the textBox1.text is the phone number ....pls help ...

rodmcleay · March 8th, 2006, 06:25 AM

In this line you do not want the escape sequences
"AT+CMGS=\\" + textBox1.Text + "\\" + "\\r";
It should look like this
"AT+CMGS=\"" + textBox1.Text + "\"\r");
The double escape sequence actually writes a \ to the string which you dont want.
But you do need a double quote around the number so it requries an escape sequence befor it ie: \"
The rest looks pretty good.

======================================
They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad.
======================================