win32 读取串口数据

#include <Windows.h>
#include <iostream>
#include <string>
#include <stdio.h>

using namespace std;
int main()
{

    //全局变量，串口句柄
    HANDLE hCom = CreateFile(L"COM3", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
    if (hCom == (HANDLE)-1)
    {
        printf_s("打开COM失败!");
        return FALSE;
    }
    else
    {
        SetupComm(hCom, 1024, 1024); //输入缓冲区和输出缓冲区的大小都是1024
        COMMTIMEOUTS TimeOuts;
        //设定读超时
        TimeOuts.ReadIntervalTimeout = 1000;
        TimeOuts.ReadTotalTimeoutMultiplier = 500;
        TimeOuts.ReadTotalTimeoutConstant = 5000;
        //设定写超时
        TimeOuts.WriteTotalTimeoutMultiplier = 500;
        TimeOuts.WriteTotalTimeoutConstant = 2000;
        SetCommTimeouts(hCom, &TimeOuts); //设置超时

        DCB dcb;
        GetCommState(hCom, &dcb);
        dcb.BaudRate = 115200; //波特率为9600
        dcb.ByteSize = 8; //每个字节有8位
        dcb.Parity = NOPARITY; //无奇偶校验位
        dcb.StopBits = TWOSTOPBITS; //两个停止位
        SetCommState(hCom, &dcb);

        PurgeComm(hCom, PURGE_TXCLEAR | PURGE_RXCLEAR);
        FILE* fd;
        while (true)
        {
            //同步读串口
            char str[256] = { 0x00 };
            DWORD wCount;//读取的字节数
            BOOL bReadStat;
            bReadStat = ReadFile(hCom, str, sizeof(str), &wCount, NULL);
            if (!bReadStat)
            {
                printf_s("读串口失败!");
                return FALSE;
            }
            else
            {
                printf_s("%s\n", str);
                fd = fopen("log.txt", "a+");
                fwrite(str, sizeof(str), strlen(str), fd);
            }
            Sleep(100);
        }
        //fclose(fd);
    }
    system("pause");
    return 0;
}