Открытие com порта через WinAPI

#include <iostream>
#include <Windows.h>
#include <thread>
#include <cstring>
#include <string>
 
int main()
{   
    std::string const str = "COM7";
    DWORD data{ 0x10 };
    DWORD data1{ 0xAA };
    HANDLE hserial = CreateFile(str.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,NULL);
    //COMMTIMEOUTS htimeSetiings;
    if (hserial == INVALID_HANDLE_VALUE)
    {
        std::cout << "Error opening port\n";
    }
 
    DCB comSetting;
 
    memset(&comSetting, 0, sizeof(comSetting));
    comSetting.DCBlength            = sizeof(DCB);
    comSetting.BaudRate             = CBR_115200;
    comSetting.ByteSize             = 8;
    comSetting.fParity              = NOPARITY;
    comSetting.StopBits             = ONESTOPBIT;
    comSetting.fBinary              = TRUE;
    comSetting.fParity              = FALSE;
    comSetting.fOutxCtsFlow         = FALSE;
    comSetting.fOutxDsrFlow         = FALSE;
    comSetting.fDtrControl          = DTR_CONTROL_DISABLE;
    comSetting.fRtsControl          = RTS_CONTROL_DISABLE;
    comSetting.fDsrSensitivity      = FALSE;
    comSetting.fTXContinueOnXoff    = FALSE;
 
    bool state = GetCommState(hserial, &comSetting);
    if (!state)
    {
        std::cout << "Error set settings DCB structure\n";
    }
 
 
    DWORD numofBytesWrite = 0;
    DWORD numofBytesRead  = 1;
    uint8_t buf{ 'a'};
    while (1)
    {
 
        if (!ReadFile(hserial, &buf, numofBytesRead, &numofBytesWrite, 0))
        {
            std::cout << "error reading";
            break;
        }
        std::cout << buf << '\n';
 
        if (!WriteFile(hserial, &data, numofBytesRead, &numofBytesWrite, 0))
        {
            std::cout << "error transmit " << (int)numofBytesWrite << '\n';
            break;
        }
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
 
    }
 
    CloseHandle(hserial);
    return 0;
}