使用libmodbus库开发modbusTcp从站(支持多个主站连接)

Chapter1 使用libmodbus库开发modbusTcp从站(支持多个主站连接)

参考链接：https://blog.csdn.net/v6543210/article/details/127426450

https://blog.csdn.net/qq_38158479/article/details/120928043

当我们需要自己搞一个C/C++版的 modbus Server时，总想像C#里面借助个好用的库来实现，但是libmodbus这个库封装的并不好用，从官方的源码中连个example都没有，能参考的也就tests目录下有几个可以借鉴。

但是仔细看了一下，random-test-server.c 还是会阻塞的，单线程。与拿来即用的标准相差甚远。

如果需要实现对多个客户端提供服务，需要参考 bandwidth-server-many-up.c

本文借鉴这篇文章，进行了一点优化，实现了可以为多个客户端提供服务的modbus tcp Server，可以拿来即用。

使用libmodbus库开发modbusTcp从站(支持多个主站连接)_酸菜。的博客-CSDN博客_libmodbus tcp

如果需要自己实现逻辑可以直接在另一个线程函数中对modbus的变量进行修改。

rdsmodbusslave.h

#ifndef RDSMODBUSSLAVE_H
#define RDSMODBUSSLAVE_H#include <iostream>
#include <thread>
#include <stdlib.h>
#include <iostream>
#include <mutex>
#include <string>
using namespace std;
/*如果是windows平台则要加载相应的静态库和头文件*/
#ifdef _WIN32
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <winsock2.h>
#include <windows.h>
//#include <modbus.h>
#pragma comment(lib, "Ws2_32.lib")
//#pragma comment(lib, "modbus.lib")
/*linux平台*/
#else
//#include <modbus/modbus.h>
#include <unistd.h>
#include <error.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/select.h>
#endif//#define  MAX_POINT  50000
#include <QObject>
#include <QThread>
#include <stdio.h>
#include <libmodbus/config.h>
#include <libmodbus/modbus.h>
#include <libmodbus/modbus-rtu.h>
#include <QTimer>
#include <QDebug>
#include <QStringList>
#include <QSerialPortInfo>
#include <QSerialPort>class RDSModbusSlave : public QObject
{Q_OBJECT
public:explicit RDSModbusSlave(QObject *parent = nullptr);RDSModbusSlave(string host="0.0.0.0", uint16_t port=502);~RDSModbusSlave();public:void recieveMessages();bool modbus_set_slave_id(int id);bool initModbus(std::string Host_Ip, int port, bool debugging);uint8_t getTab_Input_Bits(int NumBit);bool setTab_Input_Bits(int NumBit, uint8_t Value);uint16_t getHoldingRegisterValue(int registerStartaddress);float getHoldingRegisterFloatValue(int registerStartaddress);bool setHoldingRegisterValue(int registerStartaddress, uint16_t Value);bool setHoldingRegisterValue(int registerStartaddress, float Value);bool setInputRegisterValue(int registerStartaddress, uint16_t Value);bool setInputRegisterValue(int registerStartaddress, float Value);private:std::mutex slavemutex;int m_errCount{ 0 };int m_modbusSocket{ -1 };bool m_initialized{ false };modbus_t* ctx{ nullptr };modbus_mapping_t* mapping{ nullptr };/*Mapping*/int m_numBits{ 60000 };int m_numInputBits{ 60000 };int m_numRegisters{ 60000 };int m_numInputRegisters{ 60000 };public:void loadFromConfigFile();void run();signals:};/*annotation:
(1)https://www.jianshu.com/p/0ed380fa39eb
(2)typedef struct _modbus_mapping_t
{int nb_bits;                //线圈int start_bits;int nb_input_bits;          //离散输入int start_input_bits;int nb_input_registers;     //输入寄存器int start_input_registers;int nb_registers;           //保持寄存器int start_registers;uint8_t *tab_bits;uint8_t *tab_input_bits;uint16_t *tab_input_registers;uint16_t *tab_registers;
}modbus_mapping_t;*/#endif // RDSMODBUSSLAVE_H

rdsmodbusslave.cpp

#include "rdsmodbusslave.h"#ifdef _WIN32
typedef int socklen_t;
#endifRDSModbusSlave::RDSModbusSlave(QObject *parent) : QObject(parent)
{}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      Constructor* @version    v1* @return     null* @date       2021/10/6**************************************************************/
RDSModbusSlave::RDSModbusSlave(string host, uint16_t port)
{initModbus(host, port, false);//TODO：this->setHoldingRegisterValue(0, (uint16_t)0x1122);this->setHoldingRegisterValue(3, (uint16_t)0x3022);this->setHoldingRegisterValue(6, (uint16_t)0x6022);
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      Destructor* @version    v1* @return     null* @date       2021/10/6**************************************************************/
RDSModbusSlave::~RDSModbusSlave()
{modbus_mapping_free(mapping);modbus_close(ctx);modbus_free(ctx);
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      支持多个master同时连接* @version    v1* @return     null* @date       2021/10/6**************************************************************/
void RDSModbusSlave::recieveMessages()
{uint8_t query[MODBUS_TCP_MAX_ADU_LENGTH];int master_socket;int rc;fd_set refset;fd_set rdset;/* Maximum file descriptor number */int fdmax;/* Clear the reference set of socket */FD_ZERO(&refset);/* Add the server socket */FD_SET(m_modbusSocket, &refset);/* Keep track of the max file descriptor */fdmax = m_modbusSocket;while( true ){rdset = refset;if (select(fdmax+1, &rdset, NULL, NULL, NULL) == -1){perror("Server select() failure.");break;}/* Run through the existing connections looking for data to be* read */for (master_socket = 0; master_socket <= fdmax; master_socket++){if (!FD_ISSET(master_socket, &rdset)){continue;}if (master_socket == m_modbusSocket){/* A client is asking a new connection */socklen_t addrlen;struct sockaddr_in clientaddr;int newfd;/* Handle new connections */addrlen = sizeof(clientaddr);memset(&clientaddr, 0, sizeof(clientaddr));newfd = accept(m_modbusSocket, (struct sockaddr *)&clientaddr, &addrlen);if (newfd == -1){perror("Server accept() error");} else{FD_SET(newfd, &refset);if (newfd > fdmax){/* Keep track of the maximum */fdmax = newfd;}printf("New connection from %s:%d on socket %d\n", inet_ntoa(clientaddr.sin_addr), clientaddr.sin_port, newfd);}} else{modbus_set_socket(ctx, master_socket);rc = modbus_receive(ctx, query);if (rc > 0){modbus_reply(ctx, query, rc, mapping);} else if (rc == -1){/* This example server in ended on connection closing or* any errors. */printf("Connection closed on socket %d\n", master_socket);#ifdef _WIN32closesocket(master_socket);#elseclose(master_socket);#endif/* Remove from reference set */FD_CLR(master_socket, &refset);if (master_socket == fdmax){fdmax--;}}}}}m_initialized = false;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      modbus_set_slave_id* @param      id* @version    v1* @return     null* @date       2021/10/19**************************************************************/
bool RDSModbusSlave::modbus_set_slave_id(int id)
{int rc = modbus_set_slave(ctx, id);if (rc == -1){fprintf(stderr, "Invalid slave id\n");modbus_free(ctx);return false;}return true;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      modbus initialization* @param      IP/PORT/debugflag* @version    v1* @return     null* @date       2021/10/6**************************************************************/
bool RDSModbusSlave::initModbus(std::string Host_Ip = "127.0.0.1", int port = 502, bool debugging = false)
{ctx = modbus_new_tcp(Host_Ip.c_str(), port);modbus_set_debug(ctx, debugging);if (ctx == NULL){fprintf(stderr, "There was an error allocating the modbus\n");throw - 1;}m_modbusSocket = modbus_tcp_listen(ctx, 1);/*设置线圈, 离散输入, 输入寄存器, 保持寄存器个数(数组元素个数))*/mapping = modbus_mapping_new(m_numBits, m_numInputBits, m_numInputRegisters, m_numRegisters);if (mapping == NULL){fprintf(stderr, "Unable to assign mapping：%s\n", modbus_strerror(errno));modbus_free(ctx);m_initialized = false;return false;}m_initialized = true;return true;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      getTab_Input_Bits(获取输入寄存器某一位的值)* @param      NumBit(输入寄存器相应的bit位)* @version    v1* @return     null* @date       2021/10/8**************************************************************/
uint8_t RDSModbusSlave::getTab_Input_Bits(int NumBit)
{if (!m_initialized){return -1;}return mapping->tab_input_bits[NumBit];
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      setTab_Input_Bits(设置输入寄存器某一位的值)* @param      NumBit(输入寄存器的起始地址)* @param      Value(输入寄存器的值)* @version    v1* @return     null* @date       2021/10/8**************************************************************/
bool RDSModbusSlave::setTab_Input_Bits(int NumBit, uint8_t Value)
{if (NumBit > (m_numInputBits - 1)){return false;}slavemutex.lock();mapping->tab_input_bits[NumBit] = Value;slavemutex.unlock();return true;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      getRegisterValue(获取保存寄存器的值)* @param      registerStartaddress(保存寄存器的起始地址)* @version    v1* @return     null* @date       2021/10/6**************************************************************/
uint16_t RDSModbusSlave::getHoldingRegisterValue(int registerStartaddress)
{if (!m_initialized){return -1;}return mapping->tab_registers[registerStartaddress];
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      获取寄存器里的浮点数* @param      registerStartaddress寄存器起始地址* @version    v1* @return     两个uint16_t拼接而成的浮点值* @date       2021/10/6**************************************************************/
float RDSModbusSlave::getHoldingRegisterFloatValue(int registerStartaddress)
{if (!m_initialized){return -1.0f;}return modbus_get_float_badc(&mapping->tab_registers[registerStartaddress]);
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      setRegisterValue(设置保存寄存器的值，类型为uint16_t)* @param      registerStartaddress(保存寄存器的起始地址)* @param      Value(写入到保存寄存器里的值)* @version    v1* @return     null* @date       2021/10/6**************************************************************/
bool RDSModbusSlave::setHoldingRegisterValue(int registerStartaddress, uint16_t Value)
{if (registerStartaddress > (m_numRegisters - 1)){return false;}slavemutex.lock();mapping->tab_registers[registerStartaddress] = Value;slavemutex.unlock();return true;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      setRegisterFloatValue(设置浮点值)* @param      (Value：浮点值，registerStartaddress寄存器起始地址)* @version    v1* @return     null* @date       2021/10/8**************************************************************/
bool RDSModbusSlave::setHoldingRegisterValue(int registerStartaddress, float Value)
{if (registerStartaddress > (m_numRegisters - 2)){return false;}/*小端模式*/slavemutex.lock();modbus_set_float(Value, &mapping->tab_registers[registerStartaddress]);slavemutex.unlock();return true;
}bool RDSModbusSlave::setInputRegisterValue(int registerStartaddress, uint16_t Value)
{if (registerStartaddress > (m_numRegisters - 1)){return false;}slavemutex.lock();mapping->tab_input_registers[registerStartaddress] = Value;slavemutex.unlock();return true;
}bool RDSModbusSlave::setInputRegisterValue(int registerStartaddress, float Value)
{if (registerStartaddress > (m_numRegisters - 2)){return false;}/*小端模式*/slavemutex.lock();modbus_set_float(Value, &mapping->tab_input_registers[registerStartaddress]);slavemutex.unlock();return true;
}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      loadFromConfigFile* @version    v1* @return     null* @date       2021/10/18**************************************************************/
void RDSModbusSlave::loadFromConfigFile()
{}/**************************************************************** @file       RDSModbusSlave.cpp* @author     seer-txj* @brief      run* @version    v1* @return     null* @date       2021/10/18**************************************************************/
void RDSModbusSlave::run()
{std::thread loop([this](){while (true){if (m_initialized){recieveMessages();}else{m_initialized = true;}}});loop.detach();return;
}

main.cpp

#include "mainwindow.h"#include <QApplication>//#include "rdsmodbusslave.h"using namespace std;void modbusRunner(RDSModbusSlave* server)
{server->recieveMessages();
}RDSModbusSlave modServer("127.0.0.1", 502);int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();std::thread modServerThread(modbusRunner, &modServer);modServerThread.join();return a.exec();
}