C++串口通信收到的数据有一部分乱码

#include <iostream>
#include <windows.h>
using namespace std;
HANDLE hMutex;
  
DWORD WINAPI Read(LPVOID lpParamter)
{   
    //打开端口
    HANDLE hCom = CreateFileA("com7", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, 0);
    //设置超时
    COMMTIMEOUTS timeouts;
    GetCommTimeouts(hCom, &timeouts);
    timeouts.ReadIntervalTimeout = 0;
    timeouts.ReadTotalTimeoutMultiplier = 0;
    timeouts.ReadTotalTimeoutConstant = 1;
    timeouts.WriteTotalTimeoutMultiplier = 0;
    timeouts.WriteTotalTimeoutConstant = 0;
    if (!SetCommTimeouts(hCom, &timeouts))
    {
        cout<<"超时设置失败！重新";
        CloseHandle(hCom);
        return 0;
    }
  
    //取得并设置端口状态
    DCB dcb;
    GetCommState(hCom, &dcb);
    dcb.DCBlength = sizeof(DCB);
    dcb.BaudRate = 9600;
    dcb.Parity = 0;  
    dcb.ByteSize = 8;
    dcb.StopBits = ONESTOPBIT;   
    if (!SetCommState(hCom, &dcb))
    {
        cout<<"端口状态设置失败！重新";
        CloseHandle(hCom);
        return 0;
    }
  
  
    char buffer[1024];
    DWORD readsize,dwError; 
    BOOL bReadStatus;
    COMSTAT cs;
  
    WaitForSingleObject(hMutex, INFINITE);
    while(1)
    {   
        readsize = 0;
        ClearCommError(hCom,&dwError,&cs);//取得状态
        //数据能否大于所准备缓冲区
        if(cs.cbInQue>sizeof(buffer))
        {
            PurgeComm(hCom,PURGE_RXCLEAR);//清除通信端口数据
            return 0;
        }
        memset(buffer, 0 , sizeof(buffer));
        bReadStatus = ReadFile(hCom, buffer, cs.cbInQue, &readsize, 0);
        if(readsize>0)
            {
                cout<<cs.cbInQue;
                buffer[cs.cbInQue]="\0";
                std::cout<<buffer;
            }
        Sleep(5);
    }
    ReleaseMutex(hMutex);
    CloseHandle(hCom);
}
  
void main()
{
    HANDLE hThread = CreateThread(NULL, 0, Read, NULL, 0, NULL);
    hMutex = CreateMutex(NULL, FALSE, NULL);
    CloseHandle(hThread);
    while(1)
        Sleep(1000); 
}