WriteCoilRequest.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.DigitalOut;
import net.wimpi.modbus.procimg.IllegalAddressException;
import net.wimpi.modbus.procimg.ProcessImage;

/**
 * Class implementing a <tt>WriteCoilRequest</tt>.
 * The implementation directly correlates with the class 0
 * function <i>write coil (FC 5)</i>. It
 * encapsulates the corresponding request message.
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public final class WriteCoilRequest extends ModbusRequest {

    // instance attributes
    private int m_Reference;
    private boolean m_Coil;

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

    /**
     * Constructs a new <tt>WriteCoilRequest</tt>
     * instance with a given reference and state to
     * be written.
     * <p>
     *
     * @param ref the reference number of the register
     *            to read from.
     * @param b true if the coil should be set of
     *            false if it should be unset.
     */
    public WriteCoilRequest(int ref, boolean b) {
        super();
        setFunctionCode(Modbus.WRITE_COIL);
        // 4 bytes (unit id and function code is excluded)
        setDataLength(4);
        setReference(ref);
        setCoil(b);
    }// constructor

    @Override
    public ModbusResponse createResponse() {
        WriteCoilResponse response = null;
        DigitalOut dout = null;

        // 1. get process image
        ProcessImage procimg = ModbusCoupler.getReference().getProcessImage();
        // 2. get coil
        try {
            dout = procimg.getDigitalOut(this.getReference());
            // 3. set coil
            dout.set(this.getCoil());
            // if(Modbus.debug) System.out.println("set coil ref="+this.getReference()+" state=" + this.getCoil());
        } catch (IllegalAddressException iaex) {
            return createExceptionResponse(Modbus.ILLEGAL_ADDRESS_EXCEPTION);
        }
        response = new WriteCoilResponse(this.getReference(), dout.isSet());
        // 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 of the coil
     * that should be written to with this
     * <tt>ReadCoilsRequest</tt>.
     * <p>
     *
     * @param ref the reference of the coil's register.
     */
    public void setReference(int ref) {
        m_Reference = ref;
        // setChanged(true);
    }// setReference

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

    /**
     * Sets the state that should be written
     * with this <tt>WriteCoilRequest</tt>.
     * <p>
     *
     * @param b true if the coil should be set of
     *            false if it should be unset.
     */
    public void setCoil(boolean b) {
        m_Coil = b;
        // setChanged(true);
    }// setCoil

    /**
     * Returns the state that should be written
     * with this <tt>WriteCoilRequest</tt>.
     * <p>
     *
     * @return true if the coil should be set of
     *         false if it should be unset.
     */
    public boolean getCoil() {
        return m_Coil;
    }// getCoil

    @Override
    public void writeData(DataOutput dout) throws IOException {
        dout.writeShort(m_Reference);
        if (m_Coil) {
            dout.write(Modbus.COIL_ON_BYTES, 0, 2);
        } else {
            dout.write(Modbus.COIL_OFF_BYTES, 0, 2);
        }
    }

    @Override
    public void readData(DataInput din) throws IOException {
        m_Reference = din.readUnsignedShort();
        if (din.readByte() == Modbus.COIL_ON) {
            m_Coil = true;
        } else {
            m_Coil = false;
        }
        // skip last byte
        din.readByte();
    }// readData

}// class WriteCoilRequest