serial port identification with java on ubuntu

Question

I'm trying to connect a serial application on ubuntu with Java
After searching and reading resources,I add comm.jar and RXTXcomm.jar in the library.
I use the following code to identify the comports. In my system there are three ports but it is showing false in ports.hasMoreElements() method.
Kindly look into the code and help me.

String wantedPortName = "/dev/ttya";
///dev/ttyS0 و /dev/ttyS1 نیز تست شد
Enumeration portIdentifiers = CommPortIdentifier.getPortIdentifiers();
CommPortIdentifier portId = null;  // will be set if port found
while (portIdentifiers.hasMoreElements())
{
    CommPortIdentifier pid = (CommPortIdentifier) portIdentifiers.nextElement();
    if(pid.getPortType() == CommPortIdentifier.PORT_SERIAL &&
      pid.getName().equals(wantedPortName)) 
  {
    portId = pid;
    break;
  }
}
if(portId == null)
{
     System.err.println("Could not find serial port " + wantedPortName);
     System.exit(1);
}

Marcelo Amorim · Accepted Answer · 2014-02-05 03:15:15Z

1

In my case, I'm using Ubuntu, and my notebook does not have any serial or paralel ports.

So, you have to simulate this kind of port:

apt-get install socat

Run it:

socat -d -d pty,raw,echo=0, pty,raw,echo=0

According to output, pay attention to "devices" created:

2014/02/05 01:04:32 socat[7411] N PTY is /dev/pts/2
2014/02/05 01:04:32 socat[7411] N PTY is /dev/pts/3
2014/02/05 01:04:32 socat[7411] N starting data transfer loop with FDs [3,3] and [5,5]

Stop socat [CTRL]+[C] and symlink it to a location that RXTX will recognise as a device, due to "tty" prefix:

sudo ln -s /dev/pts/2 /dev/ttyUSB02
sudo ln -s /dev/pts/3 /dev/ttyUSB03

Now, run socat again

socat -d -d pty,raw,echo=0 pty,raw,echo=0

Now, using following code, you will see 2 virtual ports:

        Enumeration portList = CommPortIdentifier.getPortIdentifiers();//this line was false
        System.out.println(portList.hasMoreElements());

        while(portList.hasMoreElements()){
            System.out.println("Has more elements");
             CommPortIdentifier portId = (CommPortIdentifier) portList.nextElement();
               if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
                    System.out.println(portId.getName());
               }
               else{
                     System.out.println(portId.getName());
               }
        }

system.out:

true
Has more elements
/dev/ttyUSB03
Has more elements
/dev/ttyUSB02

answered Feb 5, 2014 at 3:15

Marcelo Amorim

1,68223 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Java Man Over a year ago

I followed your instruction but still get false at starting line. not able to entering Has more elements constraint.

Marcelo Amorim Over a year ago

Are you using ubuntu? It's a Virtual Machine?

Java Man Over a year ago

yes ubuntu.. yeah i know above commands i fired from terminal but when i used your following code.. it returns false.

Ali Akdurak Over a year ago

I think it might be about RxTx versions because they changed how they look for serial ports. rxtx.qbang.org/wiki/index.php/Trouble_shooting

cory.todd · Accepted Answer · 2013-09-08 17:52:16Z

0

It looks like you are filtering out the port you want. A /dev/tty is a special character device... not a serial port so

if(pid.getPortType() == CommPortIdentifier.PORT_SERIAL &&
  pid.getName().equals(wantedPortName))

should never match your string.

To prove this, try iterating over your available ports. I don't know if a tty can can be detected by RXTX but play with it and let us know.

Ref: http://rxtx.qbang.org/wiki/index.php/Discovering_available_comm_ports

EDIT: So you don't have any serial devices to test with? All I sat is make sure you have everything installed properly, including the properties file as described in this file.

http://rxtx.qbang.org/pub/rxtx/rxtx-2.0-7pre2/INSTALL

Once done, install a null modem emulator or find a serial device to test with.

edited Sep 8, 2013 at 17:52

answered Sep 7, 2013 at 3:52

cory.todd

5165 silver badges14 bronze badges

3 Comments

t3 nano Over a year ago

this if statment is on the while statment and while statment return false . So the program does not execute this if!!!

cory.todd Over a year ago

Sounds like it doesn't like tty! Do you have an RS-232 device or similar to test if rxtx sees it? RXTX can be picky setup and config.

t3 nano Over a year ago

Unfortunately do not have RS-232 device or similar to test rxtx please help me!

Collectives™ on Stack Overflow

serial port identification with java on ubuntu

2 Answers 2

4 Comments

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related