Serial communication Using c#

[nmsreddi]

Hi friends

I am working on c#.net . i am developing a windows application using c# 2003

aim of my application is sending and receiving sms using GSM modem.

for this i am using AxMscomm control which is there in VB6.0(telephone device)

by using this i am able to receive the data and able to send message .but the

problem is when i send the sms and after sending if i want to receive the data again

it throwing an exception Exception from HRESULT:0x800A1F45

I am using two different windows for receiving (reading messages from sim) and

other for sending sms.

i am unable to access the AxMscomm open and close (ie portopen and close)

property from other windows forms .when i tried to close the port from other

windows form(form other than the AxMscomm control is placed) it shows the

portopen property as false but internally the connection is not closed.

how to handle the properties of this control from overall my application

My partil code goes like this....
******************************************code**** ********************
SerialPort is the name of my AxMscomm control

SerialPort.CommPort=1;
if(SerialPort.PortOpen)
SerialPort.PortOpen=false;

SerialPort.RThreshold=1;
SerialPort.Settings="9600,n,8,1";
SerialPort.DTREnable=true;
SerialPort.RTSEnable=true;
SerialPort.Handshaking=MSCommLib.HandshakeConstant s.comNone;
SerialPort.InputMode=MSCommLib.InputModeConstants. comInputModeText;
SerialPort.InputLen=0;
SerialPort.NullDiscard=false;


opening the connection to rs232.............

SerialPort.PortOpen=true;

timer1.Start();

////i am using timer to read messages ffrom my sim contineously

and stop reading when i tried to send the sms. and autmatically start reading

with out manual interaction.

reading messages from sim in timer tick

SerialPort.OnComm +=new EventHandler(SerialPort_OnComm);

try
{
timer1.Stop();


if(SerialPort.InBufferCount>0)
{
Thread.Sleep(1000);

ProcessSerialportdata((string) SerialPort.Input);

timer1.Start();// commented
}
else
timer1.Start(); //commented
}
catch(Exception ex)
{
if(timer1.Enabled==true)
timer1.Stop();
else
timer1.Start();
}


private void ProcessSerialportdata(string input)
{ richTextBox1.Text="";
richTextBox1.AppendText(input+"\n");
r


if(richTextBox1.TextLength>60)
{
i=0;
j++;

}
else if((s.IndexOf("ERROR")!=-1))
{
j=1;
// timer1.Start();
SerialPort.InBufferCount=0;


}


Sending sms.................


timer1.Stop();
string cmdsend="AT+CMGS="+"xxxxxxxxxx"+Convert.ToChar(13) ;

SerialPort.Output=cmdsend;
Thread .Sleep (100);
string cmd=SerialPort.Input.ToString ();
cmdsend="";

if(cmd.IndexOf (">")>1)
{
//cmd="";
cmdsend=" sms to b send"+Convert.ToChar (26);
SerialPort.Output =cmdsend;
Thread.Sleep (10000);
cmd=SerialPort.Input.ToString ();
}



Thread.Sleep(1000);

timer1.Start();


this is the code i am using in my application

i am using timer control to my control process of reading and sending

separately using single rs232 port

Hope you will get the best

Thanks and regards

Nmsreddi