Serial Port Communication in Java

Every one is searching on Sun Microsystems website for Java serial communication library(javax.comm) for Windows and alas! no results.

To access serial port with java use RXTX Serial port Library

Experts say:

"

If you want to access the serial (RS232) or parallel port with JAVA, you need to install a platform/operating system dependent library. Install either javax.comm from SUN (Sun no longer offer's the Windows platform binaries of javax.comm, however javax.comm 2.0.3 can be used for the Windows platform, by using it in conjunction with the Win32 implementation layer provided by the RxTx project)
or better install the rxtxSerial and/or rxtxParallel library from rxtx.org (Windows, Linux, Mac OS X)."

RXTX will support all type of platforms including Windows, Linux, Mac OS X.It can be downloaded from www.rxtx.org

All platform supported downloads are availabe here http://rxtx.qbang.org/wiki/index.php/Download

Direct Download is here

After downloading this zip file unzip it. It contains libraries for Windows, Linux, Mac OS X in respective directories.Copy dll from Windows directory in your unzipped folder and paste it into "C:\Windows\System32".

It also contains RXTXcomm.jar file, copy this in to your java applications lib directory(If doesn't exist Create the lib directory).

Add reference to this jar file in your application.
Try this sample program that communicate with AT commands(you may use a mobile phone that accepts AT command).


Sample Program (ListPortClass.java)
==============================
import gnu.io.*;
import java.io.*;

public class ListPortClass
{

public static void main(String[] s)
{
try
{
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("COM1");
if (portIdentifier.isCurrentlyOwned())
{
System.out.println("Port in use!");
}
else {
System.out.println(portIdentifier.getName());

SerialPort serialPort = (SerialPort) portIdentifier.open("ListPortClass", 300);
int b = serialPort.getBaudRate();
System.out.println(Integer.toString(b));
serialPort.setSerialPortParams(300, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
OutputStream mOutputToPort = serialPort.getOutputStream();
InputStream mInputFromPort = serialPort.getInputStream();
String mValue = "AT\r";
System.out.println("beginning to Write . \r\n");
mOutputToPort.write(mValue.getBytes());
System.out.println("AT Command Written to Port. \r\n");
mOutputToPort.flush();
System.out.println("Waiting for Reply \r\n");
Thread.sleep(500);
byte mBytesIn [] = new byte[20];
mInputFromPort.read(mBytesIn);
mInputFromPort.read(mBytesIn);
String value = new String(mBytesIn);
System.out.println("Response from Serial Device: "+value);
mOutputToPort.close();
mInputFromPort.close();
}
catch (Exception ex)
{
System.out.println("Exception : " + ex.getMessage());
}

}
}

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