/***
* Copyright 2002-2010 jamod development team
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
***/
package net.wimpi.modbus.io;
import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.ModbusException;
import net.wimpi.modbus.ModbusIOException;
import net.wimpi.modbus.ModbusSlaveException;
import net.wimpi.modbus.msg.ExceptionResponse;
import net.wimpi.modbus.msg.ModbusRequest;
import net.wimpi.modbus.msg.ModbusResponse;
import net.wimpi.modbus.net.SerialConnection;
import net.wimpi.modbus.util.AtomicCounter;
import net.wimpi.modbus.util.Mutex;
/**
* Class implementing the <tt>ModbusTransaction</tt>
* interface.
*
* @author Dieter Wimberger
* @version @version@ (@date@)
*/
public class ModbusSerialTransaction
implements ModbusTransaction {
//class attributes
private static AtomicCounter c_TransactionID =
new AtomicCounter(Modbus.DEFAULT_TRANSACTION_ID);
//instance attributes and associations
private ModbusTransport m_IO;
private ModbusRequest m_Request;
private ModbusResponse m_Response;
private boolean m_ValidityCheck =
Modbus.DEFAULT_VALIDITYCHECK;
private int m_Retries = Modbus.DEFAULT_RETRIES;
private int m_TransDelayMS = Modbus.DEFAULT_TRANSMIT_DELAY;
private SerialConnection m_SerialCon;
private Mutex m_TransactionLock = new Mutex();
/**
* Constructs a new <tt>ModbusSerialTransaction</tt>
* instance.
*/
public ModbusSerialTransaction() {
}//constructor
/**
* Constructs a new <tt>ModbusSerialTransaction</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 ModbusSerialTransaction(ModbusRequest request) {
setRequest(request);
}//constructor
/**
* Constructs a new <tt>ModbusSerialTransaction</tt>
* instance with a given <tt>ModbusRequest</tt> to
* be send when the transaction is executed.
* <p/>
*
* @param con a <tt>TCPMasterConnection</tt> instance.
*/
public ModbusSerialTransaction(SerialConnection con) {
setSerialConnection(con);
}//constructor
/**
* Sets the port on which this <tt>ModbusTransaction</tt>
* should be executed.<p>
* <p/>
*
* @param con a <tt>SerialConnection</tt>.
*/
public void setSerialConnection(SerialConnection con) {
m_SerialCon = con;
m_IO = con.getModbusTransport();
}//setConnection
public int getTransactionID() {
return c_TransactionID.get();
}//getTransactionID
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 void setCheckingValidity(boolean b) {
m_ValidityCheck = b;
}//setCheckingValidity
public boolean isCheckingValidity() {
return m_ValidityCheck;
}//isCheckingValidity
public int getRetries() {
return m_Retries;
}//getRetries
public void setRetries(int num) {
m_Retries = num;
}//setRetries
/**
* Get the TransDelayMS value.
*
* @return the TransDelayMS value.
*/
public int getTransDelayMS() {
return m_TransDelayMS;
}
/**
* Set the TransDelayMS value.
*
* @param newTransDelayMS The new TransDelayMS value.
*/
public void setTransDelayMS(int newTransDelayMS) {
this.m_TransDelayMS = newTransDelayMS;
}
public void execute() throws ModbusIOException,
ModbusSlaveException,
ModbusException {
//1. assert executeability
assertExecutable();
try {
//2. Lock transaction
/**
* Note: The way this explicit synchronization is implemented at the moment,
* there is no ordering of pending threads. The Mutex will simply call notify()
* and the JVM will handle the rest.
*/
m_TransactionLock.acquire();
//3. write request, and read response,
// while holding the lock on the IO object
synchronized (m_IO) {
int tries = 0;
boolean finished = false;
//toggle the id
m_Request.setTransactionID(c_TransactionID.increment());
do {
try {
if (m_TransDelayMS > 0) {
try {
Thread.sleep(m_TransDelayMS);
} catch (InterruptedException ex) {
System.err.println("InterruptedException: " + ex.getMessage());
}
}
//write request message
m_IO.writeMessage(m_Request);
//read response message
m_Response = m_IO.readResponse();
finished = true;
} catch (ModbusIOException e) {
if (++tries >= m_Retries) {
throw e;
}
System.err.println("execute try " + tries + " error: " +
e.getMessage());
}
} while (!finished);
}
//4. deal with exceptions
if (m_Response instanceof ExceptionResponse) {
throw new ModbusSlaveException(
((ExceptionResponse) m_Response).getExceptionCode()
);
}
if (isCheckingValidity()) {
checkValidity();
}
} catch (InterruptedException ex) {
throw new ModbusIOException("Thread acquiring lock was interrupted.");
} finally {
m_TransactionLock.release();
}
}//execute
/**
* Asserts if this <tt>ModbusTCPTransaction</tt> is
* executable.
*
* @throws ModbusException if the transaction cannot be asserted.
*/
private void assertExecutable()
throws ModbusException {
if (m_Request == null ||
m_SerialCon == 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 is not valid.
*/
protected void checkValidity() throws ModbusException {
}//checkValidity
}//class ModbusSerialTransaction