前言

公司新接的一个项目，需要JAVA Modbus串口通信驱动一个设备运行，

一、Modbus是什么？

Modbus是一种串行通信协议，是Modicon公司（现在的施耐德电气Schneider Electric）于1979年为使用可编程逻辑控制器（PLC）通信而发表。Modbus已经成为工业领域通信协议的业界标准（De facto），并且现在是工业电子设备之间常用的连接方式。

Modbus协议是一个master/slave架构的协议。有一个节点是master节点，其他使用Modbus协议参与通信的节点是slave节点。每一个slave设备都有一个唯一的地址。在串行和MB+网络中，只有被指定为主节点的节点可以启动一个命令（在以太网上，任何一个设备都能发送一个Modbus命令，但是通常也只有一个主节点设备启动指令）。

MODBUS常用功能码

二、使用步骤

1.需要的资源

Java Modbus串口通信jar包资源

2.引入资源

后台引入jar,我这里是个maven项目，我是把这几个jar作为本地jar引入的，在pom中直接插入以下内容

<dependency><groupId>com.serotonin</groupId><artifactId>modbus4j</artifactId><version>3.0.5</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/modbus4j-3.0.5.jar</systemPath></dependency><dependency><groupId>com.RXTXcomm</groupId><artifactId>RXTXcomm</artifactId><version>3.0.5</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/RXTXcomm.jar</systemPath></dependency><dependency><groupId>org.scream3r</groupId><artifactId>jssc</artifactId><version>2.8.0</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/jssc-2.8.0.jar</systemPath></dependency>

resources目录下新建lib放入jar包

将 rxtxParallel.dll，rxtxSerial.dll放到JDK安装目录 jre/bin 下

3.新建代码

将这三个类直接放到项目中

SerialInputStream.java

package com.sower.pv.utils;/** To change this template, choose Tools | Templates* and open the template in the editor.*/import jssc.SerialPort;import java.io.IOException;import java.io.InputStream;/*** Class that wraps a {@link SerialPort} to provide {@link InputStream}* functionality. This stream also provides support for performing blocking* reads with timeouts.* <br>* It is instantiated by passing the constructor a {@link SerialPort} instance.* Do not create multiple streams for the same serial port unless you implement* your own synchronization.** @author Charles Hache <chalz@>** Attribution: /therealchalz/java-simple-serial-connector**/public class SerialInputStream extends InputStream {private SerialPort serialPort;private int defaultTimeout = 0;/*** Instantiates a SerialInputStream for the given {@link SerialPort} Do not* create multiple streams for the same serial port unless you implement* your own synchronization.** @param sp The serial port to stream.*/public SerialInputStream(SerialPort sp) {serialPort = sp;}/*** Set the default timeout (ms) of this SerialInputStream. This affects* subsequent calls to {@link #read()}, {@link #(int[])}, and* {@link #(int[], int, int)} The default timeout can be 'unset'* by setting it to 0.** @param time The timeout in milliseconds.*/public void setTimeout(int time) {defaultTimeout = time;}/*** Reads the next byte from the port. If the timeout of this stream has been* set, then this method blocks until data is available or until the timeout* has been hit. If the timeout is not set or has been set to 0, then this* method blocks indefinitely.*/@Overridepublic int read() throws IOException {return read(defaultTimeout);}/*** The same contract as {@link #read()}, except overrides this stream's* default timeout with the given timeout in milliseconds.** @param timeout The timeout in milliseconds.* @return The read byte.* @throws IOException On serial port error or timeout*/public int read(int timeout) throws IOException {byte[] buf = new byte[1];try {if (timeout > 0) {buf = serialPort.readBytes(1, timeout);} else {buf = serialPort.readBytes(1);}return buf[0];} catch (Exception e) {throw new IOException(e);}}/*** Non-blocking read of up to buf.length bytes from the stream. This call* behaves as read(buf, 0, buf.length) would.** @param buf The buffer to fill.* @return The number of bytes read, which can be 0.* @throws IOException on error.*/@Overridepublic int read(byte[] buf) throws IOException {return read(buf, 0, buf.length);}/*** Non-blocking read of up to length bytes from the stream. This method* returns what is immediately available in the input buffer.** @param buf The buffer to fill.* @param offset The offset into the buffer to start copying data.* @param length The maximum number of bytes to read.* @return The actual number of bytes read, which can be 0.* @throws IOException on error.*/@Overridepublic int read(byte[] buf, int offset, int length) throws IOException {if (buf.length < offset + length) {length = buf.length - offset;}int available = this.available();if (available > length) {available = length;}try {byte[] readBuf = serialPort.readBytes(available);// System.arraycopy(readBuf, 0, buf, offset, length);System.arraycopy(readBuf, 0, buf, offset, readBuf.length);return readBuf.length;} catch (Exception e) {throw new IOException(e);}}/*** Blocks until buf.length bytes are read, an error occurs, or the default* timeout is hit (if specified). This behaves as blockingRead(buf, 0,* buf.length) would.** @param buf The buffer to fill with data.* @return The number of bytes read.* @throws IOException On error or timeout.*/public int blockingRead(byte[] buf) throws IOException {return blockingRead(buf, 0, buf.length, defaultTimeout);}/*** The same contract as {@link #blockingRead(byte[])} except overrides this* stream's default timeout with the given one.** @param buf The buffer to fill.* @param timeout The timeout in milliseconds.* @return The number of bytes read.* @throws IOException On error or timeout.*/public int blockingRead(byte[] buf, int timeout) throws IOException {return blockingRead(buf, 0, buf.length, timeout);}/*** Blocks until length bytes are read, an error occurs, or the default* timeout is hit (if specified). Saves the data into the given buffer at* the specified offset. If the stream's timeout is not set, behaves as* {@link #read(byte[], int, int)} would.** @param buf The buffer to fill.* @param offset The offset in buffer to save the data.* @param length The number of bytes to read.* @return the number of bytes read.* @throws IOException on error or timeout.*/public int blockingRead(byte[] buf, int offset, int length) throws IOException {return blockingRead(buf, offset, length, defaultTimeout);}/*** The same contract as {@link #blockingRead(byte[], int, int)} except* overrides this stream's default timeout with the given one.** @param buf The buffer to fill.* @param offset Offset in the buffer to start saving data.* @param length The number of bytes to read.* @param timeout The timeout in milliseconds.* @return The number of bytes read.* @throws IOException On error or timeout.*/public int blockingRead(byte[] buf, int offset, int length, int timeout) throws IOException {if (buf.length < offset + length) {throw new IOException("Not enough buffer space for serial data");}if (timeout < 1) {return read(buf, offset, length);}try {byte[] readBuf = serialPort.readBytes(length, timeout);System.arraycopy(readBuf, 0, buf, offset, length);return readBuf.length;} catch (Exception e) {throw new IOException(e);}}@Overridepublic int available() throws IOException {int ret;try {ret = serialPort.getInputBufferBytesCount();if (ret >= 0) {return ret;}throw new IOException("Error checking available bytes from the serial port.");} catch (Exception e) {throw new IOException("Error checking available bytes from the serial port.");}}}

SerialOutputStream.java

SerialPortWrapperImpl.java

package com.sower.pv.utils;/**** Copyright (c) - Freedomotic Team http://www.freedomotic-** This file is part of Freedomotic** This Program is free software; you can redistribute it and/or modify it under* the terms of the GNU General Public License as published by the Free Software* Foundation; either version 2, or (at your option) any later version.** This Program is distributed in the hope that it will be useful, but WITHOUT* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more* details.** You should have received a copy of the GNU General Public License along with* Freedomotic; see the file COPYING. If not, see* </licenses/>.*/import com.serotonin.modbus4j.serial.SerialPortWrapper;import jssc.SerialPort;import jssc.SerialPortException;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import java.io.InputStream;import java.io.OutputStream;/****/public class SerialPortWrapperImpl implements SerialPortWrapper {private static final Logger LOG = LoggerFactory.getLogger(com.sower.pv.utils.SerialPortWrapperImpl.class);private SerialPort port;private String commPortId;private int baudRate;private int dataBits;private int stopBits;private int parity;private int flowControlIn;private int flowControlOut;public SerialPortWrapperImpl(String commPortId, int baudRate, int dataBits, int stopBits, int parity, int flowControlIn,int flowControlOut) {mPortId = commPortId;this.baudRate = baudRate;this.dataBits = dataBits;this.stopBits = stopBits;this.parity = parity;this.flowControlIn = flowControlIn;this.flowControlOut = flowControlOut;port = new SerialPort(mPortId);}@Overridepublic void close() throws Exception {port.closePort();//listeners.forEach(PortConnectionListener::closed);LOG.debug("Serial port {} closed", port.getPortName());}@Overridepublic void open() {try {port.openPort();port.setParams(this.getBaudRate(), this.getDataBits(), this.getStopBits(), this.getParity());port.setFlowControlMode(this.getFlowControlIn() | this.getFlowControlOut());//listeners.forEach(PortConnectionListener::opened);LOG.debug("Serial port {} opened", port.getPortName());} catch (SerialPortException ex) {LOG.error("Error opening port : {} for {} ", port.getPortName(), ex);}}@Overridepublic InputStream getInputStream() {return new SerialInputStream(port);}@Overridepublic OutputStream getOutputStream() {return new SerialOutputStream(port);}@Overridepublic int getBaudRate() {return baudRate;//return SerialPort.BAUDRATE_9600;}// @Override// public int getFlowControlIn() {// return flowControlIn;// //return SerialPort.FLOWCONTROL_NONE;// }//// @Override// public int getFlowControlOut() {// return flowControlOut;// //return SerialPort.FLOWCONTROL_NONE;// }public int getFlowControlIn() {return flowControlIn;}public int getFlowControlOut() {return flowControlOut;}@Overridepublic int getDataBits() {return dataBits;//return SerialPort.DATABITS_8;}@Overridepublic int getStopBits() {return stopBits;//return SerialPort.STOPBITS_1;}@Overridepublic int getParity() {return parity;//return SerialPort.PARITY_NONE;}}

调用例子，运行main方法，我这里是更改线圈的指令

package com.sower.pv.utils;import com.serotonin.modbus4j.ModbusFactory;import com.serotonin.modbus4j.ModbusMaster;import com.serotonin.modbus4j.exception.ModbusInitException;import com.serotonin.modbus4j.exception.ModbusTransportException;import com.serotonin.modbus4j.msg.*;import com.serotonin.modbus4j.serial.SerialPortWrapper;import java.util.Arrays;/*** 通过串口解析MODBUS协议* @author yaohj*/public class CollectionMain {// 设定MODBUS网络上从站地址private final static int SLAVE_ADDRESS = 68;//串行波特率private final static int BAUD_RATE = 9600;public static void main(String[] args) {SerialPortWrapper serialParameters = newSerialPortWrapperImpl("COM3", BAUD_RATE, 8, 1, 0, 0, 0);/* 创建ModbusFactory工厂实例 */ModbusFactory modbusFactory = new ModbusFactory();/* 创建ModbusMaster实例 */ModbusMaster master = modbusFactory.createRtuMaster(serialParameters);/* 初始化 */try {master.init();// readHoldingRegistersTest(master, SLAVE_ADDRESS, 99, 24);try {writeCoil(master,SLAVE_ADDRESS,1,true);} catch (Exception e) {e.printStackTrace();}readCoilTest(master,SLAVE_ADDRESS,2,1);} catch (ModbusInitException e) {e.printStackTrace();} finally {master.destroy();}}/*** 读保持寄存器上的内容* @param master 主站* @param slaveId 从站地址* @param start 起始地址的偏移量* @param len 待读寄存器的个数*/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);if (response.isException()) {System.out.println("Exception response: message=" + response.getExceptionMessage());} else {System.out.println(Arrays.toString(response.getShortData()));short[] list = response.getShortData();for (int i = 0; i < list.length; i++) {System.out.print(list[i] + " ");}}} catch (ModbusTransportException e) {e.printStackTrace();}}public static void readCoilTest(ModbusMaster master, int slaveId, int start, int len) {try {ReadCoilsRequest request=new ReadCoilsRequest(slaveId,start,len);ReadCoilsResponse response=(ReadCoilsResponse) master.send(request);if (response.isException()) {System.out.println("Exception response: message=" + response.getExceptionMessage());} else {System.out.println(Arrays.toString(response.getShortData()));System.out.println(response.getData()[0]);short[] list = response.getShortData();for (int i = 0; i < list.length; i++) {System.out.print(list[i] + " ===");}}} catch (ModbusTransportException e) {e.printStackTrace();}}public static void writeCoil(ModbusMaster master, int slaveId, int offset, boolean value) throws Exception{WriteCoilRequest request=new WriteCoilRequest(slaveId,offset,value);// ByteQueue queue = new ByteQueue();WriteCoilResponse response=(WriteCoilResponse) master.send(request);// WriteRegisterResponse response = (WriteRegisterResponse) master.send(request);if (response.isException()){System.out.println("写线圈错误，错误信息是" + response.getExceptionMessage());}else{System.out.println("写线圈指令发送成功!");}}}

总结

以上就是今天要讲的内容，本文仅仅简单介绍了Java Modbus RTU串口通信。