package com.intelligt.modbus.jlibmodbus.tcp;
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import com.intelligt.modbus.jlibmodbus.Modbus;
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import com.intelligt.modbus.jlibmodbus.exception.ModbusIOException;
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import com.intelligt.modbus.jlibmodbus.exception.ModbusNumberException;
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import com.intelligt.modbus.jlibmodbus.net.stream.base.ModbusInputStream;
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import com.intelligt.modbus.jlibmodbus.net.stream.base.ModbusOutputStream;
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import com.intelligt.modbus.jlibmodbus.utils.DataUtils;
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import java.io.IOException;
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/*
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* Copyright (C) 2016 "Invertor" Factory", JSC
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* [http://www.sbp-invertor.ru]
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*
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* This file is part of JLibModbus.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Authors: Vladislav Y. Kochedykov, software engineer.
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* email: vladislav.kochedykov@gmail.com
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*/
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final public class TcpAduHeader {
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final private byte[] buffer;
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public TcpAduHeader() {
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/*
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* 2 bytes for transaction id (often not used)
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* 2 bytes for protocol id (should be set to 0)
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* 2 bytes for pdu length (from 3 to 260)
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*/
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buffer = new byte[6];
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setProtocolId(Modbus.PROTOCOL_ID);
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}
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private void setBufferValue(int value, int offset) {
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buffer[offset++] = DataUtils.byteHigh(value);
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buffer[offset] = DataUtils.byteLow(value);
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}
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private int getPduSize() {
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return DataUtils.toShort(buffer[4], buffer[5]);
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}
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public void setPduSize(int value) {
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setBufferValue(value, 4);
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}
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public int getProtocolId() {
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return DataUtils.toShort(buffer[2], buffer[3]);
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}
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public void setProtocolId(int value) {
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setBufferValue(value, 2);
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}
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public int getTransactionId() {
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return DataUtils.toShort(buffer[0], buffer[1]);
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}
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public void setTransactionId(int value) {
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setBufferValue(value, 0);
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}
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private byte[] byteArray() {
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return buffer;
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}
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public void write(ModbusOutputStream fifo) throws ModbusIOException {
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try {
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fifo.write(byteArray());
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} catch (IOException e) {
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throw new ModbusIOException(e);
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}
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}
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public void read(ModbusInputStream fifo) throws ModbusNumberException, ModbusIOException {
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int size;
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try {
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if ((size = fifo.read(byteArray())) > 0) {
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if (getPduSize() < Modbus.MIN_PDU_LENGTH) {
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throw new ModbusNumberException("the PDU length is less than the minimum expected.", getPduSize());
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}
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if (getPduSize() > Modbus.MAX_PDU_LENGTH) {
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throw new ModbusNumberException("Maximum PDU size is reached.", getPduSize());
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}
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} else {
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throw new ModbusIOException(buffer.length + " bytes expected, but " + size + " received.");
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}
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} catch (IOException e) {
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throw new ModbusIOException(e);
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}
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}
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}
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