Java Communication:COM3 echoing back the commands

Question

Hi,
I want to send commands to the internal modem and get a reply. My code does not throw any exceptions. The problem that I am facing is that whatever command I send to COM3(the port on which the modem is connected), I get an echo of the command back. Not only the command but whatever i write to the OutputStream I get it back. Please tell me where I am going wrong.
I followed the example from here http://java.sun.com/developer/Books/javaprogramming/cookbook/11.pdf.
I am new to java communication API so need to know why COM3 is echoing back the command instead of responding.
Here is my code:
package comm;
import gnu.io.*;
import gnu.io.CommPortIdentifier;
import gnu.io.ParallelPort;
import java.io.*;
import java.util.*;
import java.io.InputStreamReader;
public class Data {
    public static final int TIMEOUTSECONDS = 30;
    public static final int BAUD = 9600;
    protected boolean debug = true;
     private ParallelPort serialPort;
    private DataInputStream is;
    private PrintStream os;
    static String name;
     static CommPortIdentifier portId;
     static CommPort thePort;
   public static void main(String args[]) throws PortInUseException
            Data d=new Data();
    Enumeration portList = CommPortIdentifier.getPortIdentifiers();
        while(portList.hasMoreElements())
            portId = (CommPortIdentifier)portList.nextElement();
               System.out.println("Name is:"+portId.getName()+" "+"Owner-"+portId.isCurrentlyOwned() +" "+"TYPE -"+portId.getPortType() );
                name = portId.getName();
   if(portId.getPortType()== CommPortIdentifier.PORT_SERIAL)
    try
          portId=CommPortIdentifier.getPortIdentifier(name);
        thePort = portId.open("DarwinSys DataComm",
          TIMEOUTSECONDS * 1000);
     SerialPort myPort = (SerialPort) thePort;
     myPort.setSerialPortParams(BAUD, SerialPort.DATABITS_8,
      SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
        } catch(Exception e)
        e.printStackTrace();
    try {
d.is = new DataInputStream(thePort.getInputStream());
d.os = new PrintStream(thePort.getOutputStream(), true);
d.os.print("ATZ");
d.os.print("\r\n");
String response = d.is.readLine();
System.out.println("Response on port:"+""+name+": "+response+""+"OwnedBy--"+portId.getCurrentOwner());
catch(Exception e)
{e.printStackTrace();}
}thanks for you help in advance
regards
Protozoa
Edited by: protozoa on Aug 20, 2008 4:01 AM

Answer 1

Hi,
Just an update on the previous post, when I sent "ATE0" it stopped echoing. BUT when I send another command it sends back null now.
here is the updated code:
d.os.print("ATE0");
Thread.currentThread().sleep(500);
d.os.print("ATZ");
Thread.currentThread().sleep(500);
d.os.print("\r\n");
String response = d.is.readLine();
System.out.println("Response on port:"+""+portId.getName()+": "+response+""+"OwnedBy--"+portId.getCurrentOwner());If I only send "ATE0" nothing is displayed, but when I sent "ATZ" next it retruns null.
regards
Protozoa