Rxtx - User contributions [en]

Writing "Hello World" to a USB to serial converter

Nigelbee — Mon, 29 Oct 2007 20:54:12 GMT

Nigelbee:

This example shows how write a Java program to write out "Hello World" to a serial port or to a USB to serial converter.

== Windows XP Computer ==

If the machine doesn't have a serial port, install a USB to serial converter following the manufacturer's instructions. Select My Computer->Properties->Hardware->Device Manager->Ports(COM&LPT)->USB - Serial Comm Port (COM4). This shows a COM port to which the device was installed - in this case COM4.

Then install Sun's Java software (JDK6 Update 3). The JDK files are placed at C:\Program Files\Java\jdk1.6.0_03\ and the runtime files are placed at C:\Program Files\Java\jre1.6.0_03\. Ensure the System Variable "path" (held in My Computer->properties->Advanced->Environment Varables->System Variables) includes ";C:\Program Files\Java\jdk1.6.0_03\bin" at the end.

Install RxTx. This involves placing rxtxSerial.dll and rxtxParallell.dll in both C:\Program Files\Java\jdk1.6.0_03\jre\bin and C:\Program Files\Java\jre1.6.0_03\bin. It also involves placing RXTXcomm.jar in both C:\Program Files\Java\jdk1.6.0_03\jre\lib\ext and C:\Program Files\Java\jre1.6.0_03\lib\ext.

Copy the SimpleWrite java program from here: [http://java.sun.com/developer/releases/javacomm/SimpleWrite.java]. Edit the file as follows:

*Change the third import statement "import javax.comm.*;" to read:

<pre> import gnu.io.*; </pre>

*Change the line "String defaultPort = "/dev/term/a";" to read:

<pre> String defaultPort = "COM4"; </pre>

(or to whichever port the USB to serial converter is installed)

This Java program can be compiled and run by typing the following at the Command Prompt:
<pre>
javac SimpleWrite.java
java SimpleWrite
</pre>

"Hello World" should then appear on the device connected to the serial port, assuming that it has been set up to receive a 9600 baud rate, 8 data bits, 1 stop bit, no parity and no handshaking.

== UBUNTU computer ==

On Unix machines the serial port ID can be found by typing:

<pre>
sudo dmesg | grep tty
</pre>

This is likely to show the port to be "/dev/ttyS0".

Sun Java RTE is installed at /usr/lib/jvm/java-1.5.0-sun-1.5.0.06/jre and RXTXcomm.jar must be placed at /usr/lib/jvm/java-1.5.0-sun-1.5.0.06/jre/lib/ext and the librxtxSerial.so and librxtxParallel.so files are placed at /usr/lib/jvm/java-1.5.0-sun-1.5.0.06/jre/lib/i386.

The defaultPort line in the SimpleWrite Java file (see above) must now be changed to:

<pre>
String defaultPort = "/dev/ttyS0";
</pre>

This Java program can be compiled and run by typing the following in the Terminal window:

<pre>
javac SimpleWrite.java
java SimpleWrite
</pre>

"Hello World" should then appear on the device connected to the serial port, assuming that it has been set up to receive a 9600 baud rate, 8 data bits, 1 stop bit, no parity and no handshaking.

Writing "Hello World" to a USB to serial converter

Nigelbee — Mon, 29 Oct 2007 20:15:56 GMT

Nigelbee:

Writing "Hello World" to a USB to serial converter

Nigelbee — Mon, 29 Oct 2007 20:05:50 GMT

Nigelbee:

Writing "Hello World" to a USB to serial converter

Nigelbee — Sun, 28 Oct 2007 21:05:46 GMT

Nigelbee:

This example shows how write a Java program to write out "Hello World" to a USB to serial converter connected to a Windows XP computer.

Firstly the USB to serial converter in installed using the manufacturer's instructions. Select My Computer->Properties->Hardware->Device Manager->Ports(COM&LPT)->USB - Serial Comm Port (COM4). This shows that the device was installed as a COM4 port.

Then install Sun's Java software (JDK6 Update 3). The JDK files are placed at C:\Program Files\Java\jdk1.6.0_03\ and the runtime files are placed at C:\Program Files\Java\jre1.6.0_03\. Ensure the System Variable "path" (held in My Computer->properties->Advanced->Environment Varables->System Variables) includes ";C:\Program Files\Java\jdk1.6.0_03\bin" at the end.

Install RxTx. This involves placing rxtxSerial.dll and rxtxParallell.dll in both C:\Program Files\Java\jdk1.6.0_03\jre\bin and C:\Program Files\Java\jre1.6.0_03\bin. It also involves placing RXTXcomm.jar in both C:\Program Files\Java\jdk1.6.0_03\jre\lib\ext and C:\Program Files\Java\jre1.6.0_03\lib\ext.

Put the following file in a folder:

<pre>
/*
* @(#)SimpleWrite.java 1.12 98/06/25 SMI
*
* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license
* to use, modify and redistribute this software in source and binary
* code form, provided that i) this copyright notice and license appear
* on all copies of the software; and ii) Licensee does not utilize the
* software in a manner which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind.
* ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
* INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND
* ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
* LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THE
* SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS
* BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES,
* HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING
* OUT OF THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control
* of aircraft, air traffic, aircraft navigation or aircraft
* communications; or in the design, construction, operation or
* maintenance of any nuclear facility. Licensee represents and
* warrants that it will not use or redistribute the Software for such
* purposes.
*/
import java.io.*;
import java.util.*;
import gnu.io.*;

/**
* Class declaration
*
*
* @author
* @version 1.10, 08/04/00
*/
public class SimpleWrite {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString = "Hello, world!";
static SerialPort serialPort;
static OutputStream outputStream;
static boolean outputBufferEmptyFlag = false;
/**
* Method declaration
*
*
* @param args
*
* @see
*/
public static void main(String[] args) {
boolean portFound = false;
String defaultPort = "COM4";

if (args.length > 0) {
defaultPort = args[0];
}

portList = CommPortIdentifier.getPortIdentifiers();

while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();

if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {

if (portId.getName().equals(defaultPort)) {
System.out.println("Found port " + defaultPort);

portFound = true;

try {
serialPort =
(SerialPort) portId.open("SimpleWrite", 2000);
} catch (PortInUseException e) {
System.out.println("Port in use.");

continue;
}

try {
outputStream = serialPort.getOutputStream();
} catch (IOException e) {}

try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}

try {
serialPort.notifyOnOutputEmpty(true);
} catch (Exception e) {
System.out.println("Error setting event notification");
System.out.println(e.toString());
System.exit(-1);
}

System.out.println(
"Writing \""+messageString+"\" to "
+serialPort.getName());

try {
outputStream.write(messageString.getBytes());
} catch (IOException e) {}

try {
Thread.sleep(2000); // Be sure data is xferred before closing
} catch (Exception e) {}
serialPort.close();
System.exit(1);
}
}
}

if (!portFound) {
System.out.println("port " + defaultPort + " not found.");
}
}

}
</pre>

Note that the third import statement has been changed to be "import gnu.io.*;"
rather than the "import javax.comm.*;" that appears in Sun's original version.

Note also that the defaultPort has been set to be COM4.

This Java program can be compiled and run by typing the following at the Command Prompt:
<pre>
javac SimpleWrite.java
java SimpleWrite
</pre>

"Hello World" should then appear on the device connected to the serial port, assuming that it has been set up to receive a 9600 baud rate, 8 data bits, 1 stop bit, no parity and no handshaking.

Writing "Hello World" to a USB to serial converter

Nigelbee — Sun, 28 Oct 2007 21:04:52 GMT

Nigelbee: New page: This example shows how write a Java program to write out "Hello World" to a USB to serial converter connected to a Windwos XP computer. Firstly the USB to serial converter in installed us...

This example shows how write a Java program to write out "Hello World" to a USB to serial converter connected to a Windwos XP computer.

Firstly the USB to serial converter in installed using the manufacturer's instructions. Select My Computer->Properties->Hardware->Device Manager->Ports(COM&LPT)->USB - Serial Comm Port (COM4). This shows that the device was installed as a COM4 port.

Then install Sun's Java software (JDK6 Update 3). The JDK files are placed at C:\Program Files\Java\jdk1.6.0_03\ and the runtime files are placed at C:\Program Files\Java\jre1.6.0_03\. Ensure the System Variable "path" (held in My Computer->properties->Advanced->Environment Varables->System Variables) includes ";C:\Program Files\Java\jdk1.6.0_03\bin" at the end.

Install RxTx. This involves placing rxtxSerial.dll and rxtxParallell.dll in both C:\Program Files\Java\jdk1.6.0_03\jre\bin and C:\Program Files\Java\jre1.6.0_03\bin. It also involves placing RXTXcomm.jar in both C:\Program Files\Java\jdk1.6.0_03\jre\lib\ext and C:\Program Files\Java\jre1.6.0_03\lib\ext.

Put the following file in a folder:

<pre>
/*
* @(#)SimpleWrite.java 1.12 98/06/25 SMI
*
* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license
* to use, modify and redistribute this software in source and binary
* code form, provided that i) this copyright notice and license appear
* on all copies of the software; and ii) Licensee does not utilize the
* software in a manner which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind.
* ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
* INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND
* ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
* LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THE
* SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS
* BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES,
* HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING
* OUT OF THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control
* of aircraft, air traffic, aircraft navigation or aircraft
* communications; or in the design, construction, operation or
* maintenance of any nuclear facility. Licensee represents and
* warrants that it will not use or redistribute the Software for such
* purposes.
*/
import java.io.*;
import java.util.*;
import gnu.io.*;

/**
* Class declaration
*
*
* @author
* @version 1.10, 08/04/00
*/
public class SimpleWrite {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString = "Hello, world!";
static SerialPort serialPort;
static OutputStream outputStream;
static boolean outputBufferEmptyFlag = false;
/**
* Method declaration
*
*
* @param args
*
* @see
*/
public static void main(String[] args) {
boolean portFound = false;
String defaultPort = "COM4";

if (args.length > 0) {
defaultPort = args[0];
}

portList = CommPortIdentifier.getPortIdentifiers();

while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();

if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {

if (portId.getName().equals(defaultPort)) {
System.out.println("Found port " + defaultPort);

portFound = true;

try {
serialPort =
(SerialPort) portId.open("SimpleWrite", 2000);
} catch (PortInUseException e) {
System.out.println("Port in use.");

continue;
}

try {
outputStream = serialPort.getOutputStream();
} catch (IOException e) {}

try {
serialPort.setSerialPortParams(9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
} catch (UnsupportedCommOperationException e) {}

try {
serialPort.notifyOnOutputEmpty(true);
} catch (Exception e) {
System.out.println("Error setting event notification");
System.out.println(e.toString());
System.exit(-1);
}

System.out.println(
"Writing \""+messageString+"\" to "
+serialPort.getName());

try {
outputStream.write(messageString.getBytes());
} catch (IOException e) {}

try {
Thread.sleep(2000); // Be sure data is xferred before closing
} catch (Exception e) {}
serialPort.close();
System.exit(1);
}
}
}

if (!portFound) {
System.out.println("port " + defaultPort + " not found.");
}
}

}
</pre>

Note that the third import statement has been changed to be "import gnu.io.*;"
rather than the "import javax.comm.*;" that appears in Sun's original version.

Note also that the defaultPort has been set to be COM4.

This Java program can be compiled and run by typing the following at the Command Prompt:
<pre>
javac SimpleWrite.java
java SimpleWrite
</pre>

"Hello World" should then appear on the device connected to the serial port, assuming that it has been set up to receive a 9600 baud rate, 8 data bits, 1 stop bit, no parity and no handshaking.

Examples

Nigelbee — Sun, 28 Oct 2007 20:22:39 GMT

Nigelbee:

Note that all the examples below require that you import the gnu.io package.

*[[Two way communcation with the serial port]]
*[[Parallel Communications]]
*[[Discovering comm ports]]
*[[Discovering available comm ports]]
*[[Writing "Hello World" to a USB to serial converter]]