WriteSingleRegisterRequest.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;

import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.ModbusCoupler;
import net.wimpi.modbus.procimg.IllegalAddressException;
import net.wimpi.modbus.procimg.ProcessImage;
import net.wimpi.modbus.procimg.Register;

/**
 * Class implementing a <tt>WriteSingleRegisterRequest</tt>.
 * The implementation directly correlates with the class 0
 * function <i>write single register (FC 6)</i>. It
 * encapsulates the corresponding request message.
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public final class WriteSingleRegisterRequest extends ModbusRequest {

    // instance attributes
    private int m_Reference;
    private Register m_Register;

    /**
     * Constructs a new <tt>WriteSingleRegisterRequest</tt>
     * instance.
     */
    public WriteSingleRegisterRequest() {
        super();
        setFunctionCode(Modbus.WRITE_SINGLE_REGISTER);
        // 4 bytes (unit id and function code is excluded)
        setDataLength(4);
    }// constructor

    /**
     * Constructs a new <tt>WriteSingleRegisterRequest</tt>
     * instance with a given reference and value to be written.
     * <p/>
     *
     * @param ref the reference number of the register
     *            to read from.
     * @param reg the register containing the data to be written.
     */
    public WriteSingleRegisterRequest(int ref, Register reg) {
        super();
        setFunctionCode(Modbus.WRITE_SINGLE_REGISTER);
        m_Reference = ref;
        m_Register = reg;
        // 4 bytes (unit id and function code is excluded)
        setDataLength(4);
    }// constructor

    @Override
    public ModbusResponse createResponse() {
        WriteSingleRegisterResponse response = null;
        Register reg = null;

        // 1. get process image
        ProcessImage procimg = ModbusCoupler.getReference().getProcessImage();
        // 2. get register
        try {
            reg = procimg.getRegister(m_Reference);
            // 3. set Register
            reg.setValue(m_Register.toBytes());
        } catch (IllegalAddressException iaex) {
            return createExceptionResponse(Modbus.ILLEGAL_ADDRESS_EXCEPTION);
        }
        response = new WriteSingleRegisterResponse(this.getReference(), reg.getValue());
        // transfer header data
        if (!isHeadless()) {
            response.setTransactionID(this.getTransactionID());
            response.setProtocolID(this.getProtocolID());
        } else {
            response.setHeadless();
        }
        response.setUnitID(this.getUnitID());
        response.setFunctionCode(this.getFunctionCode());
        return response;
    }// createResponse

    /**
     * Sets the reference of the register to be written
     * to with this <tt>WriteSingleRegisterRequest</tt>.
     * <p/>
     *
     * @param ref the reference of the register
     *            to be written to.
     */
    public void setReference(int ref) {
        m_Reference = ref;
        // setChanged(true);
    }// setReference

    /**
     * Returns the reference of the register to be
     * written to with this
     * <tt>WriteSingleRegisterRequest</tt>.
     * <p/>
     *
     * @return the reference of the register
     *         to be written to.
     */
    public int getReference() {
        return m_Reference;
    }// getReference

    /**
     * Sets the value that should be written to the
     * register with this <tt>WriteSingleRegisterRequest</tt>.
     * <p/>
     *
     * @param reg the register to be written.
     */
    public void setRegister(Register reg) {
        m_Register = reg;
    }// setRegister

    /**
     * Returns the value that should be written to the
     * register with this <tt>WriteSingleRegisterRequest</tt>.
     * <p/>
     *
     * @return the value to be written to the register.
     */
    public Register getRegister() {
        return m_Register;
    }// getRegister

    @Override
    public void writeData(DataOutput dout) throws IOException {
        dout.writeShort(m_Reference);
        dout.write(m_Register.toBytes(), 0, 2);
    }// writeData

    @Override
    public void readData(DataInput din) throws IOException {
        m_Reference = din.readUnsignedShort();
        m_Register = ModbusCoupler.getReference().getProcessImageFactory().createRegister(din.readByte(),
                din.readByte());
    }// readData

}// class WriteSingleRegisterRequest