實驗目的

JAVA應用程序通過MODBUS協議RTU模式讀寫設備

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實驗器材

西門子?s7-200?226cn?PLC?的CPU一臺；s7-200?編程電纜一條,這條電纜亦充當MODBUS的串行口上的連接線。編程電纜是USB接口的，由于此編程電纜的驅動程序安裝后即模擬了一個虛擬的串行口COM3，因此可以借助此電纜充當實際的物理連接線路

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開發環境

Jdk1.6?update?25;?STEP?7-MicroWIN?4.0;西門子S7-200的MODBUS庫

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實驗目標

讀PLC的輸入過程映像寄存器；寫PLC的V存儲區

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JAVA應用程序第三方開發包下載頁面 http://sourceforge.net/projects/modbus4j/files/modbus4j/

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Java串行口編程開發包?RXTXcomm.jar

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環境搭建

PLC充當從站，占用通訊口port0；JAVA應用程序充當主站，發起讀寫的請求并等待PLC的響應。示例程序里寫十六進制數值31（即二進制?00110001）到保持寄存器上，

PLC的Q1顯示的結果是：

Q1.0?亮

Q1.1?滅

Q1.2?滅

Q1.3?滅

Q1.4?亮

Q1.5?亮

Q1.6?滅

Q1.7?滅

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PLC從站的編程目標：MODBUS協議上的保持寄存器里的一個字節輸出到Q，以便通過PLC上的指示燈觀察。

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PLC上的梯形圖

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說明：

IB0上的值決定是否啟用MODBUS

通訊波特率9600

從站地址是5

I和Q的最大訪問個數是128

模擬量輸入最大訪問個數是32

保持寄存器可訪問1000個字

VB1上的字節輸出到Q1.0?...?Q1.7

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JAVA應用程序

import?com.serotonin.io.serial.*;

import?com.serotonin.modbus4j.*;

import?com.serotonin.modbus4j.exception.*;

import?com.serotonin.modbus4j.msg.*;

import?java.util.*;

final?class?HardneedlTest?{

????//MODBUS網絡上從站地址

????private?final?static?int?SLAVE_ADDRESS=5;

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????//串行口波特率

????private?final?static?int?BAUD_RATE?=?9600;

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????public?static?void?main(String[]?args)?throws?Exception?{

????????SerialParameters?serialParameters?=?new?SerialParameters();

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????????//設定MODBUS通訊的串行口

????????serialParameters.setCommPortId("COM3");

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????????//設定成無奇偶校驗

????????serialParameters.setParity(0);

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????????//設定成數據位是8位

????????serialParameters.setDataBits(8);

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????????//設定為1個停止位

????????serialParameters.setStopBits(1);

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????????serialParameters.setPortOwnerName("Numb?nuts");

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????????//串行口上的波特率

????????serialParameters.setBaudRate(BAUD_RATE);

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????????ModbusFactory?modbusFactory?=?new?ModbusFactory();

????????ModbusMaster?master?=?modbusFactory.createRtuMaster(serialParameters);

????????try?{

????????????master.init();

????????????readDiscreteInputTest(master,SLAVE_ADDRESS,0,8);

????????????writeRegistersTest(master,SLAVE_ADDRESS,?0,?new?short[]{0x31,0xb,0xc,0xd,0xe,0x9,?0x8,?0x7,?0x6}?);

????????????readHoldingRegistersTest(master,SLAVE_ADDRESS,0,8);

????????}

????????finally?{

????????????master.destroy();

????????}

????}

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????/**

?????*?讀開關量型的輸入信號

?????*?@param?master?主站

?????*?@param?slaveId?從站地址

?????*?@param?start?起始偏移量

?????*?@param?len?待讀的開關量的個數

?????*/

????private?static?void?readDiscreteInputTest(ModbusMaster?master,?int?slaveId,?int?start,?int?len)?{

????????try?{

????????????ReadDiscreteInputsRequest?request?=?new?ReadDiscreteInputsRequest(slaveId,?start,?len);

????????????ReadDiscreteInputsResponse?response?=?(ReadDiscreteInputsResponse)?master.send(request);

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????????????if?(response.isException())

????????????????System.out.println("Exception?response:?message="?+?response.getExceptionMessage());

????????????else

????????????????System.out.println(Arrays.toString(response.getBooleanData()));

????????}

????????catch?(ModbusTransportException?e)?{

????????????e.printStackTrace();

????????}

????}

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????/**

?????*?讀保持寄存器上的內容

?????*?@param?master?主站

?????*?@param?slaveId?從站地址

?????*?@param?start?起始地址的偏移量

?????*?@param?len?待讀寄存器的個數

?????*/

????private?static?void?readHoldingRegistersTest(ModbusMaster?master,?int?slaveId,?int?start,?int?len)?{

????????try?{

????????????ReadHoldingRegistersRequest?request?=?new?ReadHoldingRegistersRequest(slaveId,?start,?len);

????????????ReadHoldingRegistersResponse?response?=?(ReadHoldingRegistersResponse)?master.send(request);

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????????????if?(response.isException())

????????????????System.out.println("Exception?response:?message="?+?response.getExceptionMessage());

????????????else

????????????????System.out.println(Arrays.toString(response.getShortData()));

????????}

????????catch?(ModbusTransportException?e)?{

????????????e.printStackTrace();

????????}

????}

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????/**

?????*?批量寫數據到保持寄存器

?????*?@param?master?主站

?????*?@param?slaveId?從站地址

?????*?@param?start?起始地址的偏移量

?????*?@param?values?待寫數據

?????*/

????public?static?void?writeRegistersTest(ModbusMaster?master,?int?slaveId,?int?start,?short[]?values)?{

????????try?{

????????????WriteRegistersRequest?request?=?new?WriteRegistersRequest(slaveId,?start,?values);

????????????WriteRegistersResponse?response?=?(WriteRegistersResponse)?master.send(request);

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????????????if?(response.isException())

????????????????System.out.println("Exception?response:?message="?+?response.getExceptionMessage());

????????????else

????????????????System.out.println("Success");

????????}

????????catch?(ModbusTransportException?e)?{

????????????e.printStackTrace();

????????}

????}

}