//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.modbusme.io;
import net.wimpi.modbusme.Modbus;
import net.wimpi.modbusme.ModbusException;
import net.wimpi.modbusme.ModbusIOException;
import net.wimpi.modbusme.ModbusSlaveException;
import net.wimpi.modbusme.msg.ExceptionResponse;
import net.wimpi.modbusme.msg.ModbusRequest;
import net.wimpi.modbusme.msg.ModbusResponse;
import net.wimpi.modbusme.net.TCPMasterConnection;
/**
* Class implementing the <tt>ModbusTransaction</tt>
* interface.
*
* @author Dieter Wimberger
* @version 1.2rc1 (09/11/2004)
*/
public class ModbusTCPTransaction
implements ModbusTransaction {
//class attributes
private static int c_TransactionID =
Modbus.DEFAULT_TRANSACTION_ID;
//instance attributes and associations
private TCPMasterConnection m_Connection;
private ModbusTransport m_IO;
private ModbusRequest m_Request;
private ModbusResponse m_Response;
private boolean m_ValidityCheck =
Modbus.DEFAULT_VALIDITYCHECK;
private boolean m_Reconnecting = Modbus.DEFAULT_RECONNECTING;
private int m_Retries = Modbus.DEFAULT_RETRIES;
/**
* Constructs a new <tt>ModbusTCPTransaction</tt>
* instance.
*/
public ModbusTCPTransaction() {
}//constructor
/**
* Constructs a new <tt>ModbusTCPTransaction</tt>
* instance with a given <tt>ModbusRequest</tt> to
* be send when the transaction is executed.
* <p>
* @param request a <tt>ModbusRequest</tt> instance.
*/
public ModbusTCPTransaction(ModbusRequest request) {
setRequest(request);
}//constructor
/**
* Constructs a new <tt>ModbusTCPTransaction</tt>
* instance with a given <tt>TCPMasterConnection</tt> to
* be used for transactions.
* <p>
* @param con a <tt>TCPMasterConnection</tt> instance.
*/
public ModbusTCPTransaction(TCPMasterConnection con) {
setConnection(con);
}//constructor
/**
* Sets the connection on which this <tt>ModbusTransaction</tt>
* should be executed.<p>
* An implementation should be able to
* handle open and closed connections.<br>
* <p>
* @param con a <tt>TCPMasterConnection</tt>.
*/
public void setConnection(TCPMasterConnection con) {
m_Connection = con;
m_IO = con.getModbusTransport();
}//setConnection
public void setRequest(ModbusRequest req) {
m_Request = req;
//m_Response = req.getResponse();
}//setRequest
public ModbusRequest getRequest() {
return m_Request;
}//getRequest
public ModbusResponse getResponse() {
return m_Response;
}//getResponse
public int getTransactionID() {
return c_TransactionID;
}//getTransactionID
public void setCheckingValidity(boolean b) {
m_ValidityCheck = b;
}//setCheckingValidity
public boolean isCheckingValidity() {
return m_ValidityCheck;
}//isCheckingValidity
/**
* Sets the flag that controls whether a
* connection is openend and closed for
* <b>each</b> execution or not.
* <p>
* @param b true if reconnecting, false otherwise.
*/
public void setReconnecting(boolean b) {
m_Reconnecting = b;
}//setReconnecting
/**
* Tests if the connection will be openend
* and closed for <b>each</b> execution.
* <p>
* @return true if reconnecting, false otherwise.
*/
public boolean isReconnecting() {
return m_Reconnecting;
}//isReconnecting
public int getRetries() {
return m_Retries;
}//getRetries
public void setRetries(int num) {
m_Retries = num;
}//setRetries
public void execute() throws ModbusIOException,
ModbusSlaveException,
ModbusException {
//1. assert executeability
assertExecutable();
//2. open the connection if not connected
if (!m_Connection.isConnected()) {
try {
m_Connection.connect();
} catch (Exception ex) {
throw new ModbusIOException("Connecting failed.");
}
}
//3. Retry transaction m_Retries times, in case of
//I/O Exception problems.
int retryCounter = 0;
while (retryCounter <= m_Retries) {
try {
//3. write request, and read response,
// while holding the lock on the IO object
synchronized (m_IO) {
//write request message
m_IO.writeMessage(m_Request);
//read response message
m_Response = m_IO.readResponse();
break;
}
} catch (ModbusIOException ex) {
if (retryCounter == m_Retries) {
throw new ModbusIOException("Executing transaction failed (tried " + m_Retries + " times)");
} else {
retryCounter++;
continue;
}
}
}
//4. deal with "application level" exceptions
if (m_Response instanceof ExceptionResponse) {
throw new ModbusSlaveException(
((ExceptionResponse) m_Response).getExceptionCode()
);
}
//5. close connection if reconnecting
if (isReconnecting()) {
m_Connection.close();
}
if (isCheckingValidity()) {
checkValidity();
}
//toggle the id
toggleTransactionID();
}//execute
/**
* Asserts if this <tt>ModbusTCPTransaction</tt> is
* executable.
*
* @throws ModbusException if the transaction cannot be asserted
* as executable.
*/
private void assertExecutable()
throws ModbusException {
if (m_Request == null ||
m_Connection == null) {
throw new ModbusException(
"Assertion failed, transaction not executable"
);
}
}//assertExecuteable
/**
* Checks the validity of the transaction, by
* checking if the values of the response correspond
* to the values of the request.
*
* @throws ModbusException if the transaction was not valid.
*/
private void checkValidity() throws ModbusException {
//1.check transaction number
//if(m_Request.getTransactionID()!=m_Response.getTransactionID()) {
//}
}//checkValidity
/**
* Toggles the transaction identifier, to ensure
* that each transaction has a distinctive
* identifier.<br>
* When the maximum value of 65535 has been reached,
* the identifiers will start from zero again.
*/
private void toggleTransactionID() {
if (isCheckingValidity()) {
if (c_TransactionID == Modbus.MAX_TRANSACTION_ID) {
c_TransactionID = 0;
} else {
c_TransactionID++;
}
}
m_Request.setTransactionID(getTransactionID());
}//toggleTransactionID
}//class ModbusTCPTransaction