ModBus RTU协议 -->c语言实现

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <stdint.h>


int init_port(int serialPort)
{
const char *serialPort = "/dev/ttyAMA3";
    int serial_fd ;

    // Open the serial port
    serial_fd = open(serialPort, O_RDWR | O_NOCTTY);
    if (serial_fd == -1) {
        handleError("Error opening serial port");
    }
 struct termios tty;
    if (tcgetattr(serial_fd, &tty) != 0) {
        perror("Error from tcgetattr");
        close(serial_fd);
        return -1;
    }

    // 设置为非规范模式（二进制模式）
    tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
    tty.c_oflag &= ~OPOST;
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
    tty.c_cflag &= ~(CSIZE | PARENB);
    tty.c_cflag |= CS8;

    // 设置波特率
    cfsetospeed(&tty, B9600);
    cfsetispeed(&tty, B9600);

 if (tcsetattr(serial_fd, TCSANOW, &tty) != 0) {
        perror("Error from tcsetattr");
        close(serial_fd);
        return -1;
    }
    return serial_fd;

}


int pm_get(int serialPort)
{
    unsigned char modbus_setframe[] = {0x01,0x03,0x00,0x07,0x00,0x03,0xB4,0x0A};
     write(serialPort, modbus_setframe, 8);
// Read data from the serial port
    char buffer[20];
    ssize_t bytesRead=0;
    bytesRead = read(serialPort, buffer, 20);
     if (bytesRead == 0) {
        printf("No data received.\n");
    } else {
        handleError("Error reading from serial port");
    }
    uint8_t address =  buffer[0];
    uint8_t functioncode = buffer[1];
    uint16_t PM1_0 = (buffer[3] << 8) | buffer[4];
    uint16_t PM2_5 = (buffer[5] << 8) | buffer[6];
    uint16_t PM10_0 = (buffer[7] << 8) | buffer[8];

    //此处省略crc校验

    printf("addr:0x%02X,Funcode:0x%02X \n",address,functioncode);
    printf("PW1.5 data is %d ,PWD2.5 data is %d,PWD10 data is %d\n",PM1_0,PM2_5,PM10_0);
    return 0;
}


int main() {
    int ret;
    int len;
    int serialPort = open("/dev/ttyAMA3", O_RDWR);
    if (serialPort == -1) {
        perror("Error opening serial port");
        exit(1);
    }
    // 配置串口参数
   ret=init_port(serialPort);

   pm_get(serialPort );
   close(serialPort);
}