WriteMultipleRegistersResponse.java

/***
 * 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.msg;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

/**
 * Class implementing a <tt>WriteMultipleRegistersResponse</tt>.
 * The implementation directly correlates with the class 0
 * function <i>read multiple registers (FC 16)</i>. It encapsulates
 * the corresponding response message.
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public final class WriteMultipleRegistersResponse extends ModbusResponse {

    // instance attributes
    private int m_WordCount;
    private int m_Reference;

    /**
     * Constructs a new <tt>WriteMultipleRegistersResponse</tt>
     * instance.
     */
    public WriteMultipleRegistersResponse() {
        super();
    }// constructor

    /**
     * Constructs a new <tt>WriteMultipleRegistersResponse</tt>
     * instance.
     *
     * @param reference the offset to start reading from.
     * @param wordcount the number of words (registers) to be read.
     */
    public WriteMultipleRegistersResponse(int reference, int wordcount) {
        super();
        m_Reference = reference;
        m_WordCount = wordcount;
        setDataLength(4);
    }// constructor

    /**
     * Sets the reference of the register to start writing to
     * with this <tt>WriteMultipleRegistersResponse</tt>.
     * <p>
     *
     * @param ref the reference of the register
     *            to start writing to as <tt>int</tt>.
     */
    private void setReference(int ref) {
        m_Reference = ref;
    }// setReference

    /**
     * Returns the reference of the register to start
     * writing to with this
     * <tt>WriteMultipleRegistersResponse</tt>.
     * <p>
     *
     * @return the reference of the register
     *         to start writing to as <tt>int</tt>.
     */
    public int getReference() {
        return m_Reference;
    }// getReference

    /**
     * Returns the number of bytes that have been written.
     * <p>
     *
     * @return the number of bytes that have been read
     *         as <tt>int</tt>.
     */
    public int getByteCount() {
        return m_WordCount * 2;
    }// getByteCount

    /**
     * Returns the number of words that have been read.
     * The returned value should be half of
     * the byte count of the response.
     * <p>
     *
     * @return the number of words that have been read
     *         as <tt>int</tt>.
     */
    public int getWordCount() {
        return m_WordCount;
    }// getWordCount

    /**
     * Sets the number of words that have been returned.
     * <p>
     *
     * @param count the number of words as <tt>int</tt>.
     */
    private void setWordCount(int count) {
        m_WordCount = count;
    }// setWordCount

    @Override
    public void writeData(DataOutput dout) throws IOException {
        dout.writeShort(m_Reference);
        dout.writeShort(getWordCount());
    }// writeData

    @Override
    public void readData(DataInput din) throws IOException {

        setReference(din.readUnsignedShort());
        setWordCount(din.readUnsignedShort());
        // NOTE: register values are not echoed

        // update data length
        setDataLength(4);
    }// readData

}// class WriteMultipleRegistersResponse