jssc always timeout

Question

So I'm trying to send command to my device using JSSC library, but haven't succeeded yet. This is my code, build from several example online:

static SerialPort tPort = new SerialPort("/dev/ttyUSB0");
public static void main(String[] args) {
    String[] portNames = SerialPortList.getPortNames();
    for (String tPortName : portNames) {
        System.out.println(tPortName);
    }

    try {
        tPort.openPort();
        tPort.setParams(
                SerialPort.BAUDRATE_9600, 
                SerialPort.DATABITS_8, 
                SerialPort.STOPBITS_1, 
                SerialPort.PARITY_NONE);
        tPort.setFlowControlMode(SerialPort.FLOWCONTROL_XONXOFF_IN|SerialPort.FLOWCONTROL_XONXOFF_OUT);

        int mask = SerialPort.MASK_RXCHAR + SerialPort.MASK_CTS + SerialPort.MASK_DSR; //Prepare mask
        tPort.writeBytes("AT".getBytes()); //Write data to port
        tPort.setEventsMask(mask); //Set mask
        tPort.addEventListener(new SerialPortReader()); //Add SerialPortEventListener

    } catch (SerialPortException ex) {
        ex.printStackTrace(System.out);
    }
}

static class SerialPortReader implements SerialPortEventListener {
    public void serialEvent(SerialPortEvent event) {
        if(event.isRXCHAR()){//If data is available
            System.out.println("available!");
            if(event.getEventValue() == 10){//Check bytes count in the input buffer
                //Read data, if 10 bytes available 
                try {
                    byte buffer[] = tPort.readBytes(10);
                } catch (SerialPortException ex) {
                    System.out.println(ex);
                }
            }
        } else if(event.isCTS()){//If CTS line has changed state
            if(event.getEventValue() == 1){//If line is ON
                System.out.println("CTS - ON");
            } else {
                System.out.println("CTS - OFF");
            }
        } else if(event.isDSR()){ //If DSR line has changed state
            if(event.getEventValue() == 1){ //If line is ON
                System.out.println("DSR - ON");
            } else {
                System.out.println("DSR - OFF");
            }
        }
    }
}

when I ran it, the only output I got was

CTS - OFF
DSR - OFF

with no apparent response from the device. But when I use minicom using this configuration

    lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
    x A -    Serial Device      : /dev/ttyUSB0                              x
    x B - Lockfile Location     : /var/lock                                 x
    x C -   Callin Program      :                                           x
    x D -  Callout Program      :                                           x
    x E -    Bps/Par/Bits       : 9600 8N1                                  x
    x F - Hardware Flow Control : No                                        x
    x G - Software Flow Control : No                                        x
    x                                                                       x
    x    Change which setting?                                              x
    mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj

the device return something.

What did I do wrong?

edit: I tried reading with timeout method, and the method keep throwing timeout.

Answer 1

At the very least you should call addEventListener BEFORE sending to the port with writeBytes.

You should also set .setFlowControl(SerialPort.FLOWCONTROL_NONE) if you want exactly the same settings as minicom.

Answer 2

Apparently I missed the spec which specify that in order to be considered a message, the input string must end with CR. After adding the CR character, the device has returned the something. stupid mistake (doh).