//License
/***
* Java Modbus Library (jamod)
* Copyright (c) 2002-2004, jamod development team
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the author nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
***/
package net.wimpi.modbus.net;
import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.ModbusCoupler;
import net.wimpi.modbus.ModbusIOException;
import net.wimpi.modbus.io.ModbusTransport;
import net.wimpi.modbus.msg.ModbusRequest;
import net.wimpi.modbus.msg.ModbusResponse;
import net.wimpi.modbus.util.SerialParameters;
/**
* Class that implements a ModbusTCPListener.<br>
* If listening, it accepts incoming requests
* passing them on to be handled.
*
* @author Dieter Wimberger
* @version 1.2rc1 (09/11/2004)
*/
public class ModbusSerialListener {
//Members
private boolean m_Listening; //Flag for toggling listening/!listening
private SerialConnection m_SerialCon;
private static int c_RequestCounter = 0; //counter for amount of requests
/**
* Constructs a new <tt>ModbusSerialListener</tt> instance.
*
* @param params a <tt>SerialParameters</tt> instance.
*/
public ModbusSerialListener(SerialParameters params) {
m_SerialCon = new SerialConnection(params);
//System.out.println("Created connection.");
listen();
}//constructor
/**
* Listen to incoming messages.
*/
private void listen() {
try {
m_Listening = true;
m_SerialCon.open();
//System.out.println("Opened Serial connection.");
ModbusTransport transport = m_SerialCon.getModbusTransport();
do {
if (m_Listening) {
try {
//1. read the request
ModbusRequest request = transport.readRequest();
ModbusResponse response = null;
//test if Process image exists
if (ModbusCoupler.getReference().getProcessImage() == null) {
response =
request.createExceptionResponse(Modbus.ILLEGAL_FUNCTION_EXCEPTION);
} else {
response = request.createResponse();
}
if (Modbus.debug)
System.out.println("Request:" + request.getHexMessage());
if (Modbus.debug)
System.out.println("Response:" + response.getHexMessage());
transport.writeMessage(response);
count();
} catch (ModbusIOException ex) {
ex.printStackTrace();
continue;
}
}
//ensure nice multithreading behaviour on specific platforms
} while (true);
} catch (Exception e) {
//FIXME: this is a major failure, how do we handle this
e.printStackTrace();
}
}//listen
/**
* Sets the listening flag of this <tt>ModbusTCPListener</tt>.
*
* @param b true if listening (and accepting incoming connections),
* false otherwise.
*/
public void setListening(boolean b) {
m_Listening = b;
}//setListening
/**
* Tests if this <tt>ModbusTCPListener</tt> is listening
* and accepting incoming connections.
*
* @return true if listening (and accepting incoming connections),
* false otherwise.
*/
public boolean isListening() {
return m_Listening;
}//isListening
private void count() {
c_RequestCounter++;
if (c_RequestCounter == REQUESTS_TOGC) {
System.gc();
c_RequestCounter = 0;
}
}//count
private static final int REQUESTS_TOGC = 15;
}//class ModbusTCPListener