打印到文件的值不正确.串口通信程序

这段代码应该向COM3发送命令，向文件发送响应-然后从COM5读取一定数量的字符并将其写入文件。奇怪的值正在打印。

我想我看代码的时间太长了。任何帮助都会很棒。

#include <Windows.h>
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main()
{
    ofstream myfile;
    myfile.open ("example.txt", 'w');
    HANDLE hSerial = CreateFile("COM3",GENERIC_READ | GENERIC_WRITE,0,0,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0);
    HANDLE hSerial2 = CreateFile("COM5",GENERIC_READ | GENERIC_WRITE,0,0,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0);
    if(hSerial==INVALID_HANDLE_VALUE)
        std::cout << "Insert error message";
    DCB dcbSerialParams = {0};
    dcbSerialParams.DCBlength=sizeof(dcbSerialParams);
    if (!GetCommState(hSerial, &dcbSerialParams)) 
        std::cout << "Insert error message";
    dcbSerialParams.BaudRate=CBR_9600;
    dcbSerialParams.ByteSize=8;
    dcbSerialParams.StopBits=ONESTOPBIT;
    dcbSerialParams.Parity=NOPARITY;
    if (!SetCommState(hSerial,&dcbSerialParams))
        std::cout << "Insert error message";

    COMMTIMEOUTS timeouts={0};
    timeouts.ReadIntervalTimeout=50;
    timeouts.ReadTotalTimeoutConstant=50;
    timeouts.ReadTotalTimeoutMultiplier=10;
    timeouts.WriteTotalTimeoutConstant=50;
    timeouts.WriteTotalTimeoutMultiplier=10;
    if(!SetCommTimeouts(hSerial, &timeouts))
        std::cout << "Insert error message";

int i = 0;
while(i < 10)
{
char szBuff[50+1] = {0};
char lzBuff[400] = {0};
char wzBuff[14] = {"AT+CSQr"};
DWORD dZBytesRead = 0;
DWORD dwBytesRead = 0;

if(!WriteFile(hSerial, wzBuff, 7, &dZBytesRead, NULL))
    std::cout << "Write error";
if(!ReadFile(hSerial, szBuff, 50, &dwBytesRead, NULL))
    std::cout << "Read Error";
if(!ReadFile(hSerial2, lzBuff, 400, &dZBytesRead, NULL))
    std::cout << "Read Error";

std::string test2 = std::string(lzBuff).substr(300,10);
//std:: cout << szBuff;
if(dwBytesRead > 9)
{
    std::string test = std::string(szBuff).substr(8,3);
    myfile << test <<endl << endl << endl;
std::cout << test << endl;
}
if(dZBytesRead > 200)
{
    std::string test2 = std::string(lzBuff).substr(1,10);
    myfile << test2 << 'n' << 'n';
}
Sleep(500);
i++;
}
myfile.close();
return 0;
}