文章目录
😏1. 项目介绍
官网:https://libmodbus.org/
项目Github地址:https://github.com/stephane/libmodbus
Libmodbus
是一个用于通信协议 Modbus
的开源 C 语言库
。Modbus 是一种常用的工业通信协议,用于在自动化设备之间进行数据交换。Libmodbus 提供了一组函数和工具,使开发者能够轻松地实现 Modbus 通信功能。
以下是 Libmodbus
库的一些主要特点和功能:
Libmodbus
是一个广泛使用的 Modbus 库,适用于各种工业自动化和物联网应用。
😊2. 环境配置
下面进行环境配置:
# apt安装
sudo apt install libmodbus-dev
# 编译
g++ -o main main.cpp -lmodbus
😆3. 使用说明
下面进行使用分析:
Modbus RTU串行读取和写入示例:
#include <iostream>
#include <modbus/modbus.h>
int main() {
modbus_t* modbusContext;
uint16_t readBuffer[64]; // 用于存储读取的数据
const int slaveId = 1; // 从机 ID
const int registerAddress = 0; // 寄存器地址
const int numRegisters = 1; // 寄存器数量
const int coilAddress = 0; // 线圈地址
const int numCoils = 1; // 线圈数量
// 初始化 - 设备号、波特率、校验位、数据位、停止位
modbusContext = modbus_new_rtu("/dev/ttyUSB0", 9600, 'N', 8, 1);
if (modbusContext == nullptr) {
std::cerr << "Failed to create Modbus context" << std::endl;
return 1;
}
// 打开 Modbus 连接
if (modbus_connect(modbusContext) == -1) {
std::cerr << "Modbus connection failed: " << modbus_strerror(errno) << std::endl;
modbus_free(modbusContext);
return 1;
}
// 读取寄存器
int rc = modbus_read_registers(modbusContext, registerAddress, numRegisters, readBuffer);
if (rc == -1) {
std::cerr << "Failed to read Modbus registers: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Read value: " << readBuffer[0] << std::endl;
}
// 写入寄存器
const uint16_t writeValue = 1234;
rc = modbus_write_register(modbusContext, registerAddress, writeValue);
if (rc == -1) {
std::cerr << "Failed to write Modbus register: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Write successful" << std::endl;
}
// 读取线圈状态
uint8_t coilStatus;
rc = modbus_read_bits(modbusContext, coilAddress, numCoils, &coilStatus);
if (rc == -1) {
std::cerr << "Failed to read Modbus coils: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Coil value: " << static_cast<int>(coilStatus) << std::endl;
}
// 写入线圈状态
const uint8_t writeValue2 = 1;
rc = modbus_write_bit(modbusContext, coilAddress, writeValue2);
if (rc == -1) {
std::cerr << "Failed to write Modbus coil: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Write successful" << std::endl;
}
// 关闭 Modbus 连接
modbus_close(modbusContext);
modbus_free(modbusContext);
return 0;
}
Modbus TCP以太网读取写入示例:
#include <iostream>
#include <modbus/modbus.h>
int main() {
modbus_t* modbusContext;
const char* ipAddress = "192.168.1.100"; // Modbus TCP 从机的 IP 地址
const int port = 502; // Modbus TCP 端口号
const int slaveId = 1; // 从机 ID
modbusContext = modbus_new_tcp(ipAddress, port);
if (modbusContext == nullptr) {
std::cerr << "Failed to create Modbus context" << std::endl;
return 1;
}
// 打开 Modbus 连接
if (modbus_connect(modbusContext) == -1) {
std::cerr << "Modbus connection failed: " << modbus_strerror(errno) << std::endl;
modbus_free(modbusContext);
return 1;
}
// 读取线圈状态
const int coilAddress = 0; // 线圈地址
const int numCoils = 1; // 线圈数量
uint8_t coilStatus[numCoils];
int rc = modbus_read_bits(modbusContext, coilAddress, numCoils, coilStatus);
if (rc == -1) {
std::cerr << "Failed to read Modbus coils: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Coil value: " << static_cast<int>(coilStatus[0]) << std::endl;
}
// 写入线圈状态
const uint8_t writeValue = 1;
rc = modbus_write_bit(modbusContext, coilAddress, writeValue);
if (rc == -1) {
std::cerr << "Failed to write Modbus coil: " << modbus_strerror(errno) << std::endl;
} else {
std::cout << "Write successful" << std::endl;
}
// 关闭 Modbus 连接
modbus_close(modbusContext);
modbus_free(modbusContext);
return 0;
}
以上。