一.什么是modbus

  Modbus是由Modicon(现为施耐德电气公司的一个品牌)在1979年发明的,是全球第一个真正用于工业现场的总线协议。
ModBus网络是一个工业通信系统,由带智能终端的可编程序控制器和计算机通过公用线路或局部专用线路连接而成。其系统结构既包括硬件、亦包括软件。它可应用于各种数据采集和过程监控。
  ModBus网络只有一个主机,所有通信都由他发出。网络可支持247个之多的远程从属控制器,但实际所支持的从机数要由所用通信设备决定。采用这个系统,各PC可以和中心主机交换信息而不影响各PC执行本身的控制任务。

二.Java实现modbus协议通讯

Java编程中,使用modbus4j实现Java中的modbus协议通讯
核心依赖:
modbus4j.jar
commons-lang3-3.0.jar
//下载地址代码里有

Java读取工具类
import com.serotonin.modbus4j.BatchRead;
import com.serotonin.modbus4j.BatchResults;
import com.serotonin.modbus4j.ModbusFactory;
import com.serotonin.modbus4j.ModbusMaster;
import com.serotonin.modbus4j.code.DataType;
import com.serotonin.modbus4j.exception.ErrorResponseException;
import com.serotonin.modbus4j.exception.ModbusInitException;
import com.serotonin.modbus4j.exception.ModbusTransportException;
import com.serotonin.modbus4j.ip.IpParameters;
import com.serotonin.modbus4j.locator.BaseLocator;

/**
 * modbus通讯工具类,采用modbus4j实现
 * 
 * @author lxq
 * @dependencies modbus4j-3.0.3.jar
 * @website https://github.com/infiniteautomation/modbus4j
 */
public class Modbus4jUtil {
	/**
	 * 获取master
	 * 
	 * @return
	 * @throws ModbusInitException
	 */
	public static ModbusMaster getMaster() throws ModbusInitException {
		IpParameters params = new IpParameters();
		params.setHost("localhost");
		params.setPort(502);

		ModbusMaster master = new ModbusFactory().createTcpMaster(params, false);
		master.init();

		return master;
	}

	/**
	 * 读取[01 Coil Status 0x]类型 开关数据
	 * 
	 * @param slaveId
	 *            slaveId
	 * @param offset
	 *            位置
	 * @return 读取值
	 * @throws ModbusTransportException
	 *             异常
	 * @throws ErrorResponseException
	 *             异常
	 * @throws ModbusInitException
	 *             异常
	 */
	public static Boolean readCoilStatus(int slaveId, int offset)
			throws ModbusTransportException, ErrorResponseException, ModbusInitException {
		// 01 Coil Status
		BaseLocator<Boolean> loc = BaseLocator.coilStatus(slaveId, offset);
		Boolean value = getMaster().getValue(loc);
		return value;
	}

	/**
	 * 读取[02 Input Status 1x]类型 开关数据
	 * 
	 * @param slaveId
	 * @param offset
	 * @return
	 * @throws ModbusTransportException
	 * @throws ErrorResponseException
	 * @throws ModbusInitException
	 */
	public static Boolean readInputStatus(int slaveId, int offset)
			throws ModbusTransportException, ErrorResponseException, ModbusInitException {
		// 02 Input Status
		BaseLocator<Boolean> loc = BaseLocator.inputStatus(slaveId, offset);
		Boolean value = getMaster().getValue(loc);
		return value;
	}

	/**
	 * 读取[03 Holding Register类型 2x]模拟量数据
	 * 
	 * @param slaveId
	 *            slave Id
	 * @param offset
	 *            位置
	 * @param dataType
	 *            数据类型,来自com.serotonin.modbus4j.code.DataType
	 * @return
	 * @throws ModbusTransportException
	 *             异常
	 * @throws ErrorResponseException
	 *             异常
	 * @throws ModbusInitException
	 *             异常
	 */
	public static Number readHoldingRegister(int slaveId, int offset, int dataType)
			throws ModbusTransportException, ErrorResponseException, ModbusInitException {
		// 03 Holding Register类型数据读取
		BaseLocator<Number> loc = BaseLocator.holdingRegister(slaveId, offset, dataType);
		Number value = getMaster().getValue(loc);
		return value;
	}

	/**
	 * 读取[04 Input Registers 3x]类型 模拟量数据
	 * 
	 * @param slaveId
	 *            slaveId
	 * @param offset
	 *            位置
	 * @param dataType
	 *            数据类型,来自com.serotonin.modbus4j.code.DataType
	 * @return 返回结果
	 * @throws ModbusTransportException
	 *             异常
	 * @throws ErrorResponseException
	 *             异常
	 * @throws ModbusInitException
	 *             异常
	 */
	public static Number readInputRegisters(int slaveId, int offset, int dataType)
			throws ModbusTransportException, ErrorResponseException, ModbusInitException {
		// 04 Input Registers类型数据读取
		BaseLocator<Number> loc = BaseLocator.inputRegister(slaveId, offset, dataType);
		Number value = getMaster().getValue(loc);
		return value;
	}

	/**
	 * 批量读取使用方法
	 * 
	 * @throws ModbusTransportException
	 * @throws ErrorResponseException
	 * @throws ModbusInitException
	 */
	public static void batchRead() throws ModbusTransportException, ErrorResponseException, ModbusInitException {

		BatchRead<Integer> batch = new BatchRead<Integer>();

		batch.addLocator(0, BaseLocator.holdingRegister(1, 1, DataType.FOUR_BYTE_FLOAT));
		batch.addLocator(1, BaseLocator.inputStatus(1, 0));

		ModbusMaster master = getMaster();

		batch.setContiguousRequests(false);
		BatchResults<Integer> results = master.send(batch);
		System.out.println(results.getValue(0));
		System.out.println(results.getValue(1));
	}

	/**
	 * 测试
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		try {
			// 01测试
			Boolean v011 = readCoilStatus(1, 0);
			Boolean v012 = readCoilStatus(1, 1);
			Boolean v013 = readCoilStatus(1, 6);
			System.out.println("v011:" + v011);
			System.out.println("v012:" + v012);
			System.out.println("v013:" + v013);
			// 02测试
			Boolean v021 = readInputStatus(1, 0);
			Boolean v022 = readInputStatus(1, 1);
			Boolean v023 = readInputStatus(1, 2);
			System.out.println("v021:" + v021);
			System.out.println("v022:" + v022);
			System.out.println("v023:" + v023);

			// 03测试
			Number v031 = readHoldingRegister(1, 1, DataType.FOUR_BYTE_FLOAT);// 注意,float
			Number v032 = readHoldingRegister(1, 3, DataType.FOUR_BYTE_FLOAT);// 同上
			System.out.println("v031:" + v031);
			System.out.println("v032:" + v032);

			// 04测试
			Number v041 = readInputRegisters(1, 1, DataType.FOUR_BYTE_FLOAT);//
			Number v042 = readInputRegisters(1, 3, DataType.FOUR_BYTE_FLOAT);//
			System.out.println("v041:" + v041);
			System.out.println("v042:" + v042);
			//批量读取
			batchRead();
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

三、测试

使用ModbusSlave模拟modbus协议
slave中模拟数据如下
modbus slave模拟数据
运行工具类的main方法:
11:14:54.547 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 01 00 00 00 01 
11:14:54.550 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.598 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 01 01 01 
11:14:54.600 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 01 00 01 00 01 
11:14:54.600 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.650 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 01 01 00 
11:14:54.652 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 01 00 06 00 01 
11:14:54.652 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.703 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 01 01 01 
v011:true
v012:false
v013:true
11:14:54.704 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 02 00 00 00 01 
11:14:54.704 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.755 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 02 01 01 
11:14:54.757 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 02 00 01 00 01 
11:14:54.757 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.807 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 02 01 00 
11:14:54.810 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 02 00 02 00 01 
11:14:54.810 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.860 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 02 01 01 
v021:true
v022:false
v023:true
11:14:54.866 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 03 00 01 00 02 
11:14:54.866 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.915 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 07 01 03 04 40 20 00 00 
11:14:54.917 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 03 00 03 00 02 
11:14:54.917 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:54.967 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 07 01 03 04 41 28 00 00 
v031:2.5
v032:10.5
11:14:54.971 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 04 00 01 00 02 
11:14:54.971 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:55.020 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 07 01 04 04 3F C0 00 00 
11:14:55.021 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 04 00 03 00 02 
11:14:55.021 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:55.072 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 07 01 04 04 40 40 00 00 
v041:1.5
v042:3.0
11:14:55.074 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 00 00 00 00 06 01 02 00 00 00 01 
11:14:55.074 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:55.123 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 00 00 00 00 04 01 02 01 01 
11:14:55.125 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Encap Request: 00 01 00 00 00 06 01 03 00 01 00 02 
11:14:55.125 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Sending on port: 502
11:14:55.179 [main] DEBUG com.serotonin.modbus4j.ip.tcp.TcpMaster - Response: 00 01 00 00 00 07 01 03 04 40 20 00 00 
2.5
true

观察输出结果与 slave上的模拟数据一致

四、Java通过modbus4j对数据的写入

Modbus4jWriteUtils.java
package com.leftso.project.demo.modbus4j;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.serotonin.modbus4j.ModbusFactory;
import com.serotonin.modbus4j.ModbusMaster;
import com.serotonin.modbus4j.code.DataType;
import com.serotonin.modbus4j.exception.ErrorResponseException;
import com.serotonin.modbus4j.exception.ModbusInitException;
import com.serotonin.modbus4j.exception.ModbusTransportException;
import com.serotonin.modbus4j.ip.IpParameters;
import com.serotonin.modbus4j.locator.BaseLocator;
import com.serotonin.modbus4j.msg.ModbusResponse;
import com.serotonin.modbus4j.msg.WriteCoilRequest;
import com.serotonin.modbus4j.msg.WriteCoilResponse;
import com.serotonin.modbus4j.msg.WriteCoilsRequest;
import com.serotonin.modbus4j.msg.WriteCoilsResponse;
import com.serotonin.modbus4j.msg.WriteRegisterRequest;
import com.serotonin.modbus4j.msg.WriteRegisterResponse;
import com.serotonin.modbus4j.msg.WriteRegistersRequest;

/**
 * modbus4j写入数据
 * 
 * @author xq
 *
 */
public class Modbus4jWriteUtils {
	static Log log = LogFactory.getLog(Modbus4jWriteUtils.class);
	/**
	 * 工厂。
	 */
	static ModbusFactory modbusFactory;
	static {
		if (modbusFactory == null) {
			modbusFactory = new ModbusFactory();
		}
	}

	/**
	 * 获取tcpMaster
	 * 
	 * @return
	 * @throws ModbusInitException
	 */
	public static ModbusMaster getMaster() throws ModbusInitException {
		IpParameters params = new IpParameters();
		params.setHost("localhost");
		params.setPort(502);

		ModbusMaster tcpMaster = modbusFactory.createTcpMaster(params, false);
		tcpMaster.init();

		return tcpMaster;
	}

	/**
	 * 写 [01 Coil Status(0x)]写一个 function ID = 5
	 * 
	 * @param slaveId
	 *            slave的ID
	 * @param writeOffset
	 *            位置
	 * @param writeValue
	 *            值
	 * @return 是否写入成功
	 * @throws ModbusTransportException
	 * @throws ModbusInitException
	 */
	public static boolean writeCoil(int slaveId, int writeOffset, boolean writeValue)
			throws ModbusTransportException, ModbusInitException {
		// 获取master
		ModbusMaster tcpMaster = getMaster();
		// 创建请求
		WriteCoilRequest request = new WriteCoilRequest(slaveId, writeOffset, writeValue);
		// 发送请求并获取响应对象
		WriteCoilResponse response = (WriteCoilResponse) tcpMaster.send(request);
		if (response.isException()) {
			return false;
		} else {
			return true;
		}
	}

	/**
	 * 写[01 Coil Status(0x)] 写多个 function ID = 15
	 * 
	 * @param slaveId
	 *            slaveId
	 * @param startOffset
	 *            开始位置
	 * @param bdata
	 *            写入的数据
	 * @return 是否写入成功
	 * @throws ModbusTransportException
	 * @throws ModbusInitException
	 */
	public static boolean writeCoils(int slaveId, int startOffset, boolean[] bdata)
			throws ModbusTransportException, ModbusInitException {
		// 获取master
		ModbusMaster tcpMaster = getMaster();
		// 创建请求
		WriteCoilsRequest request = new WriteCoilsRequest(slaveId, startOffset, bdata);
		// 发送请求并获取响应对象
		WriteCoilsResponse response = (WriteCoilsResponse) tcpMaster.send(request);
		if (response.isException()) {
			return false;
		} else {
			return true;
		}

	}

	/***
	 * 写[03 Holding Register(4x)] 写一个 function ID = 6
	 * 
	 * @param slaveId
	 * @param writeOffset
	 * @param writeValue
	 * @return
	 * @throws ModbusTransportException
	 * @throws ModbusInitException
	 */
	public static boolean writeRegister(int slaveId, int writeOffset, short writeValue)
			throws ModbusTransportException, ModbusInitException {
		// 获取master
		ModbusMaster tcpMaster = getMaster();
		// 创建请求对象
		WriteRegisterRequest request = new WriteRegisterRequest(slaveId, writeOffset, writeValue);
		WriteRegisterResponse response = (WriteRegisterResponse) tcpMaster.send(request);
		if (response.isException()) {
			log.error(response.getExceptionMessage());
			return false;
		} else {
			return true;
		}

	}

	/**
	 * 
	 * 写入[03 Holding Register(4x)]写多个 function ID=16
	 * 
	 * @param slaveId
	 *            modbus的slaveID
	 * @param startOffset
	 *            起始位置偏移量值
	 * @param sdata
	 *            写入的数据
	 * @return 返回是否写入成功
	 * @throws ModbusTransportException
	 * @throws ModbusInitException
	 */
	public static boolean writeRegisters(int slaveId, int startOffset, short[] sdata)
			throws ModbusTransportException, ModbusInitException {
		// 获取master
		ModbusMaster tcpMaster = getMaster();
		// 创建请求对象
		WriteRegistersRequest request = new WriteRegistersRequest(slaveId, startOffset, sdata);
		// 发送请求并获取响应对象
		ModbusResponse response = tcpMaster.send(request);
		if (response.isException()) {
			log.error(response.getExceptionMessage());
			return false;
		} else {
			return true;
		}
	}

	/**
	 * 写入数字类型的模拟量(如:写入Float类型的模拟量、Double类型模拟量、整数类型Short、Integer、Long)
	 * 
	 * @param slaveId
	 * @param offset
	 * @param value
	 *            写入值,Number的子类,例如写入Float浮点类型,Double双精度类型,以及整型short,int,long
	 * @param registerCount
	 *            ,com.serotonin.modbus4j.code.DataType
	 * @throws ModbusTransportException
	 * @throws ErrorResponseException
	 * @throws ModbusInitException
	 */
	public static void writeHoldingRegister(int slaveId, int offset, Number value, int dataType)
			throws ModbusTransportException, ErrorResponseException, ModbusInitException {
		// 获取master
		ModbusMaster tcpMaster = getMaster();
		// 类型
		BaseLocator<Number> locator = BaseLocator.holdingRegister(slaveId, offset, dataType);
		tcpMaster.setValue(locator, value);
	}

	public static void main(String[] args) {
		try {
			//@formatter:off
			// 测试01
//			boolean t01 = writeCoil(1, 0, true);
//			System.out.println("T01:" + t01);

			// 测试02
//			boolean t02 = writeCoils(1, 0, new boolean[] { true, false, true });
//			System.out.println("T02:" + t02);

			// 测试03
//			short v = -3;
//			boolean t03 = writeRegister(1, 0, v);
//			System.out.println("T03:" + t03);
			// 测试04
//			boolean t04 = writeRegisters(1, 0, new short[] { -3, 3, 9 });
//			System.out.println("t04:" + t04);
			//写模拟量
			writeHoldingRegister(1,0, 10.1f, DataType.FOUR_BYTE_FLOAT);
			
			//@formatter:on
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

浮点类型数据写入

modbus协议中常见功能代码说明:
function ID/code说明
 
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