public class Main {
    final static private int slaveId = 49;
    public static void main(String[] args) {
        String portName = args.length>0 ? args[0] : "/dev/ttyS4";
        try {
            Modbus.setLogLevel(Modbus.LogLevel.LEVEL_DEBUG);
            SerialParameters serialParameters = new SerialParameters(
                    portName,
                    SerialPort.BaudRate.BAUD_RATE_9600,
                    8,
                    1,
                    SerialPort.Parity.NONE
            );
            SerialUtils.setSerialPortFactory(new SerialPortFactoryJSSC());
            ModbusSlave slave = ModbusSlaveFactory.createModbusSlaveRTU(serialParameters) ;
            slave.setServerAddress(slaveId);
            slave.setBroadcastEnabled(true);
            slave.setReadTimeout(args.length>1 ? Integer.valueOf(args[1]) : 10000);

            FrameEventListener listener = new FrameEventListener() {
                @Override
                public void frameSentEvent(FrameEvent event) {
                    System.out.println("frame sent " + DataUtils.toAscii(event.getBytes()));
                }
                @Override
                public void frameReceivedEvent(FrameEvent event) {
                    System.out.println("frame recv " + DataUtils.toAscii(event.getBytes()));
                }
            };
            slave.addListener(listener);
            ModbusHoldingRegisters holdingRegisters = new ModbusHoldingRegisters(1000);
            for (int i = 0; i < holdingRegisters.getQuantity(); i++) {
                holdingRegisters.set(i, i + 1);
            }
            holdingRegisters.setFloat32At(0, (float)(Math.PI * Math.random()));
            slave.getDataHolder().setInputRegisters(holdingRegisters);
            slave.getDataHolder().setHoldingRegisters(new ModbusHoldingRegisters(1000));
            slave.listen();
        } catch (ModbusProtocolException | ModbusIOException | SerialPortException e) {
            e.printStackTrace();
        }
    }
}