按位取值是指該測(cè)點(diǎn)的數(shù)據(jù)類型為16位有/無符號(hào)、32位有/無符號(hào)時(shí)，將讀到的值按BIT位解析，起始位和終止位相同時(shí)，表示解析1位數(shù)據(jù)，值為0或1；起始位和終止位根據(jù)數(shù)據(jù)類型不同，最小0，最大31；

例如讀到的值為十進(jìn)制的10，那么將其轉(zhuǎn)換為二進(jìn)制為0000 1010，其第0位(起始位和終止位都配置成0)為0，第1為1，第2位為0，第3位為1。

杭州領(lǐng)祺科技智能物聯(lián)網(wǎng)關(guān)支持MODBUS采集、轉(zhuǎn)發(fā)、監(jiān)聽，支持485串口MODBUS異構(gòu)組網(wǎng)，支持多上位機(jī)WEB組態(tài)同時(shí)接收信息，支持MODBUS和M-BUS協(xié)議轉(zhuǎn)換，MODBUS TCP MODBUS RTU等各種協(xié)議轉(zhuǎn)換、混采。

在線幫助文檔

https://dingiiot.com/help-doc/drive_page/modbus-rtu%E9%87%87%E9%9B%86/

設(shè)備地址：從設(shè)備的地址編號(hào)

CRC校驗(yàn)：用來確認(rèn)接收消息完整性和正確性

Java代碼取值實(shí)現(xiàn)

網(wǎng)上有許多開源的modbos工具包，例如modbus4j、jamod等。這里選用jamod，以Modbus RTU通訊為例

maven依賴如下，同時(shí)需要在C://Windows//System32目錄下，放入RXTXcomm.jar、rxtxParallel.dll、rxtxSerial.dll三個(gè)文件，用來實(shí)現(xiàn)串口通信

net.wimpi

jamod

1.2

創(chuàng)建和串口的連接

public class ModBusConnection {

public static SerialConnection getSerialConnection() throws Exception {

SerialParameters parameters = new SerialParameters();

// 串口名稱

parameters.setPortName("COM2");

// 波特率

parameters.setBaudRate(9600);

// 數(shù)據(jù)位8位

parameters.setDatabits(SerialPort.DATABITS_8);

// 停止位2位

parameters.setStopbits(SerialPort.STOPBITS_2);

// 無奇偶校驗(yàn)位

parameters.setParity(SerialPort.PARITY_NONE);

// rtu模式，取代默認(rèn)的ascii模式

parameters.setEncoding("rtu");

SerialConnection connection = new SerialConnection(parameters);

connection.open();

return connection;

}

}

創(chuàng)建request取數(shù)工具類

public class ModBusUtil {

/**

* 讀寫 boolean類型 function code 01

* @param connection con

* @param param param

* @return BitVector

*/

public static BitVector readCoils(SerialConnection connection, ModBusRequest param) throws Exception {

ReadCoilsRequest request = new ReadCoilsRequest(param.getAddressNo(), param.getWordCount());

request.setUnitID(param.getSlaveId());

ReadCoilsResponse response = (ReadCoilsResponse) getResponse(connection, request);

return response.getCoils();

}

/**

* 只讀 boolean類型 function code 02

* @param connection con

* @param param param

* @return BitVector

*/

public static BitVector readInputDiscretes(SerialConnection connection, ModBusRequest param) throws Exception {

ReadInputDiscretesRequest request = new ReadInputDiscretesRequest(param.getAddressNo(), param.getWordCount());

request.setUnitID(param.getSlaveId());

ReadInputDiscretesResponse response = (ReadInputDiscretesResponse) getResponse(connection, request);

return response.getDiscretes();

}

/**

* 讀寫 int類型 function code 03

* @param connection con

* @param param param

* @return InputRegister

*/

public static InputRegister[] readMultipleRegisters(SerialConnection connection, ModBusRequest param) throws Exception {

ReadMultipleRegistersRequest request = new ReadMultipleRegistersRequest(param.getAddressNo(), param.getWordCount());

request.setUnitID(param.getSlaveId());

ReadMultipleRegistersResponse response = (ReadMultipleRegistersResponse) getResponse(connection, request);

return response.getRegisters();

}

/**

* 只讀 int類型 function code 04

* @param connection con

* @param param param

* @return InputRegister

*/

public static InputRegister[] readInputRegisters(SerialConnection connection, ModBusRequest param) throws Exception {

// 寄存器地址編號(hào) 屬性數(shù)據(jù)數(shù)量

ReadInputRegistersRequest request = new ReadInputRegistersRequest(param.getAddressNo(), param.getWordCount());

// 從設(shè)備編號(hào)

request.setUnitID(param.getSlaveId());

ReadInputRegistersResponse response = (ReadInputRegistersResponse) getResponse(connection, request);

return response.getRegisters();

}

/**

* 獲取response

* @param connection con

* @param request req

* @return ModbusResponse

*/

private static ModbusResponse getResponse(SerialConnection connection, ModbusRequest request) throws Exception {

ModbusSerialTransaction transaction = new ModbusSerialTransaction(connection);

transaction.setRequest(request);

transaction.execute();

return transaction.getResponse();

}

}

main方法測(cè)試類

public class SerialPortTest {

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

SerialConnection connection = ModBusConnection.getSerialConnection();

ModBusRequest param = new ModBusRequest();

// 從設(shè)備id編號(hào)

param.setSlaveId(1);

// 寄存器地址編號(hào) 這邊使用了function 01，addressNo=0表示寄存器地址為00001

param.setAddressNo(0);

// 讀取數(shù)據(jù)個(gè)數(shù)

param.setWordCount(1);

InputRegister[] registers = ModBusUtil.readInputRegisters(connection, param);

for (InputRegister register : registers) {

System.out.println(register.getValue());

}

connection.close();

}

}