1. modbus在java中的使用，首先maven的pom中引入modbus4j包

    			
     
      com.infiniteautomation
     	 		
     
      modbus4j
     	        
     
      3.0.3
             
    

    2. 我们创建类：ModBus4JTCPClient，创建ModbusMaster连接对象，以及读取寄存器方法

package io.powerx.test;import org.apache.commons.lang3.StringUtils;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.WriteRegisterRequest;import com.serotonin.modbus4j.msg.WriteRegistersRequest;public class ModBus4JTCPClient {	private ModbusFactory modbusFactory;	public ModbusFactory getModbusFactory() {		if (modbusFactory == null) {			modbusFactory = new ModbusFactory();		}		return modbusFactory;	}	/**	 * 	 * @param ip	 * @param port	 * @return	 * @throws ModbusInitException	 */	public ModbusMaster getMaster(String ip, int port) throws ModbusInitException {		ModbusMaster m = null;		IpParameters tcpParameters = new IpParameters();		tcpParameters.setHost(ip);		tcpParameters.setPort(port);		m = getModbusFactory().createTcpMaster(tcpParameters, false);		m.setTimeout(2000);		m.init();		return m;	}	/**	 * Holding Register类型	 * 	 * @param master	 * @param modbusId	 * @param registerId	 * @param registerNumber	 * @param analysisFlag	 * @return	 * @throws ModbusTransportException	 * @throws ErrorResponseException	 * @throws ModbusInitException	 */	public Number readHoldingRegister(ModbusMaster master, int modbusId, int registerId, int registerNumber,			String analysisFlag) throws ModbusTransportException, ErrorResponseException, ModbusInitException {		Number value = null;		if ("u".equals(analysisFlag)) {			value = holdingRegister_UNSIGNED(master, modbusId, registerId, registerNumber);		} else if ("s".equals(analysisFlag)) {			value = holdingRegister_SIGNED(master, modbusId, registerId, registerNumber);		}		return value;	}	public Number holdingRegister_UNSIGNED(ModbusMaster master, int modbusId, int registerId, int registerNumber)			throws ModbusTransportException, ErrorResponseException {		BaseLocator
    
      loc = BaseLocator.holdingRegister(modbusId, registerId - 1,				(registerNumber == 1) ? DataType.TWO_BYTE_INT_UNSIGNED : DataType.FOUR_BYTE_INT_UNSIGNED);		return master.getValue(loc);	}	public Number holdingRegister_SIGNED(ModbusMaster master, int modbusId, int registerId, int registerNumber)			throws ModbusTransportException, ErrorResponseException {		return master.getValue(BaseLocator.holdingRegister(modbusId, registerId - 1,				(registerNumber == 1) ? DataType.TWO_BYTE_INT_SIGNED : DataType.FOUR_BYTE_INT_SIGNED));	}	// Input Registers	public void readInputRegisters(ModbusMaster master, int registerId, int registerNumber, int modbusId,			String analysisFlag) throws ModbusTransportException, ErrorResponseException, ModbusInitException {		Number value = null;         //z代表是正数，s代表可能是负数		if ("z".equals(analysisFlag)) {			value = inputRegister_UNSIGNED(master, modbusId, registerId, registerNumber);		} else if ("f".equals(analysisFlag)) {			value = inputRegister_SIGNED(master, modbusId, registerId, registerNumber);		}	}	public Number inputRegister_UNSIGNED(ModbusMaster master, int modbusId, int registerId, int registerNumber)			throws ModbusTransportException, ErrorResponseException {		return master.getValue(BaseLocator.inputRegister(modbusId, registerId - 1,				(registerNumber == 1) ? DataType.TWO_BYTE_INT_UNSIGNED : DataType.FOUR_BYTE_INT_UNSIGNED));	}	public Number inputRegister_SIGNED(ModbusMaster master, int modbusId, int registerId, int registerNumber)			throws ModbusTransportException, ErrorResponseException {		return master.getValue(BaseLocator.inputRegister(modbusId, registerId - 1,				(registerNumber == 1) ? DataType.TWO_BYTE_INT_SIGNED : DataType.FOUR_BYTE_INT_SIGNED));	}	/**	 * 写入寄存器	 * 	 * @param master	 * @param registerId	 * @param modbusId	 * @param sdata	 * @return	 * @throws ModbusTransportException	 * @throws ModbusInitException	 */	public boolean writeRegister(ModbusMaster master, int registerId, int modbusId, short sdata)			throws ModbusTransportException, ModbusInitException {		// 创建请求对象		WriteRegisterRequest request = new WriteRegisterRequest(modbusId, registerId - 1, sdata);		// 发送请求并获取响应对象		ModbusResponse response = master.send(request);		if (response.isException()) {			return false;		} else {			return true;		}	}	public boolean writeRegisters(ModbusMaster master, int registerId, int modbusId, short[] sdata)			throws ModbusTransportException, ModbusInitException {		// 创建请求对象		WriteRegistersRequest request = new WriteRegistersRequest(modbusId, registerId - 1, sdata);		// 发送请求并获取响应对象		ModbusResponse response = master.send(request);		if (response.isException()) {			return false;		} else {			return true;		}	}	public void writeHoldingRegister(ModbusMaster master, int registerId, int modbusId, Number writeValue, int dataType)			throws ModbusTransportException, ErrorResponseException, ModbusInitException {		BaseLocator
     
       locator = BaseLocator.holdingRegister(modbusId, registerId - 1,				(dataType == 1) ? DataType.TWO_BYTE_INT_UNSIGNED : DataType.FOUR_BYTE_INT_UNSIGNED);		master.setValue(locator, writeValue);	}}
     
    

    3. 我们试一下在main方法中调用

int registerId=100;		int modbusId=1;		ModBus4JTCPClient modbusTcp = new ModBus4JTCPClient();				ModbusMaster master = modbusTcp.getMaster("localhost", 502);	//192.168.1.108						modbusTcp.readInputRegisters(master, registerId, 1, modbusId, "u");