I have Ubuntu 11.10 kernel 3.0.0-12-generic-pae and librxtx-java version 2.2pre2-8 . In the code below, it displays my serial ports correctly. Do you now have a USB port for the serial converter? you need to check which port is used by the converter. Using the sample application below, you can try something like java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2 java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2
Make sure you have the correct permission in the ttySXX or ttyUSBXX file, in / dev /.
crw-rw
These serial ports are displayed on my system, and the user who wants to run the application must be under the group number. To add yourself, use:
sudo usermod -a -G dialout username
You should now be in the dialout group.
import gnu.io.CommPortIdentifier; import gnu.io.NoSuchPortException; import gnu.io.PortInUseException; import gnu.io.SerialPort; import gnu.io.SerialPortEvent; import gnu.io.SerialPortEventListener; import gnu.io.UnsupportedCommOperationException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.Enumeration; import java.util.TooManyListenersException; public class GetCommPorts { static Enumeration<CommPortIdentifier> portList; static CommPortIdentifier portId; static SerialPort serialPort; static OutputStream outputStream; static boolean outputBufferEmptyFlag = false; public static class SerialReader implements SerialPortEventListener { private InputStream in; private byte[] buffer = new byte[1024]; public SerialReader(InputStream in) { this.in = in; } @Override /** * treat \n as end of block. */ public void serialEvent(SerialPortEvent ev) { int data; try { int len = 0; while ( (data = in.read()) > -1) { if (data == '\n') { break; } buffer[len++] = (byte) data; } System.out.println(new String(buffer, 0, len)); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); System.exit(-1); } } } public static class SerialWriter implements Runnable { OutputStream out; public SerialWriter(OutputStream out) { this.out = out; } @Override public void run() { try { int c = 0; while ( (c = System.in.read()) > -1) { this.out.write(c); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); System.exit(-1); } } } private static String getPortTypeName ( int portType ) { switch ( portType ) { case CommPortIdentifier.PORT_I2C: return "I2C"; case CommPortIdentifier.PORT_PARALLEL: return "Parallel"; case CommPortIdentifier.PORT_RAW: return "Raw"; case CommPortIdentifier.PORT_RS485: return "RS485"; case CommPortIdentifier.PORT_SERIAL: return "Serial"; default: return "unknown type"; } } private static void listPorts() { @SuppressWarnings("unchecked") java.util.Enumeration<CommPortIdentifier> portEnum = CommPortIdentifier.getPortIdentifiers(); while ( portEnum.hasMoreElements() ) { CommPortIdentifier portIdentifier = portEnum.nextElement(); System.out.println(portIdentifier.getName() + " - " + getPortTypeName(portIdentifier.getPortType()) ); if (portIdentifier.getPortType() == 1) { try { serialPort = (SerialPort) portIdentifier.open(portIdentifier.getName(), 3000); } catch (PortInUseException e) { System.err.print("port in use"); continue; } System.out.println("Baud is " + serialPort.getBaudRate()); System.out.println("Bits is " + serialPort.getDataBits()); System.out.println("Stop is " + serialPort.getStopBits()); System.out.println("Par is " + serialPort.getParity()); serialPort.close(); } } } private static int doReadWrite(String portName) { CommPortIdentifier portIdentifier; try { portIdentifier = CommPortIdentifier.getPortIdentifier(portName); if (portIdentifier.isCurrentlyOwned()) { System.err.println("error: port is currently in use"); return -1; } SerialPort sport = (SerialPort) portIdentifier.open(portName, 3000); sport.setSerialPortParams(57600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE); InputStream in = sport.getInputStream(); OutputStream out = sport.getOutputStream(); (new Thread(new SerialWriter(out))).start(); sport.addEventListener(new SerialReader(in)); sport.notifyOnDataAvailable(true); } catch (NoSuchPortException e) { e.printStackTrace(); return -1; } catch (PortInUseException e) { e.printStackTrace(); return -1; } catch (UnsupportedCommOperationException e) { e.printStackTrace(); return -1; } catch (IOException e) { e.printStackTrace(); return -1; } catch (TooManyListenersException e) { e.printStackTrace(); return -1; } return 0; } static void showHelp() { System.out.println("Usage " + GetCommPorts.class.getName() + "N"); System.out.println("1 read and write from the serial port"); System.out.println("2 list all serial ports in the system"); System.out.println("default show this help "); } public static void main(String[] args) { int operation = 0; try { if (args.length != 1) { showHelp(); return; } operation = Integer.parseInt(args[0]); } catch (NumberFormatException e) { } switch (operation) { case 1: doReadWrite("/dev/ttyUSB0"); break; case 2: listPorts(); break; default: showHelp(); } } }
Exiting this application:
$ java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2 /dev/ttyS1 - Serial Baud is 9600 Bits is 8 Stop is 1 Par is 0 /dev/ttyS0 - Serial Baud is 9600 Bits is 8 Stop is 1 Par is 0