Issues receiving in RXTX

Question

I\'ve been using RXTX for about a year now, without too many problems. I just started a new program to interact with a new piece of hardware, so I reused the connect() metho

Answer 1

OK, sorry it's taken me so long to come back to this question. Here's how I got things working.

Note: This method will NOT work for everyone, please read below before copy/pasting into your own code

public void connect(CommPortIdentifier portId) throws Failure {
    if (portId == null)
        throw new Failure("No port set");

    try { port = (SerialPort) portId.open(getClass().getName(), 10000); } 
    catch (PortInUseException e) {
        throw new Failure("Port in use by " + e.currentOwner,e); }

    try {
        port.setSerialPortParams(9600, SerialPort.DATABITS_8,
                SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
        port.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN
                              | SerialPort.FLOWCONTROL_RTSCTS_OUT);
    } catch (UnsupportedCommOperationException e) { throw new Failure(e); }

    port.setRTS(true);

    // More setup
}

So, in my case, the problem was that my particular device requires RTS flow control. Other devices may require different things (CTS, XON/XOFF), so check that device's manual. By default, RXTX disables all flow control mechanisms (unlike Hypertrm or other programs). Enabling each one is a two-step process.

1. Once you have a SerialPort object, call the setFlowControlMode() method, and bitwise-OR ('|') the necessary SerialPort.FLOWCONTROL_ constants
2. Set the appropriate flow control to true or false (like I did with port.setRTS(true))

For the others with similar problems, if this doesn't work, I suggest

1. Using a serial port monitoring program like Serial Port Monitor and/or PortMon (both Windows) to see what is actually going on.
2. Emailing the RXTX developers at rxtx@qbang.org (they are very helpful)