Функция чтения ком порта

DLL_API DWORD COM_Read( DWORD hOpenContext, LPVOID pBuffer, DWORD Count )
{
    if (hOpenContext != OPEN_CONTEXT)
        return 0;
}
    DWORD dwBytes = 0;
    ReadFile(hComm, pBuffer, Count, &dwBytes, NULL);
       char* pCh = (char*)pBuffer;
     if (dwBytes <=19)
     {memset (pCh,0,dwBytes);dwBytes = 0;}
    else
     pBuffer=pCh;
     return dwBytes;
}

int Measure_thread::COMOpen(int port_number,int baudrate,int parity,int databits,int stopbits,int read_wait_timeout,bool use_dtr,HANDLE * comport)
{
    String portname;
    DCB dcb;
    COMMTIMEOUTS timeouts;
 
    portname="COM"+IntToStr(port_number);
    *comport=CreateFile(portname.c_str(),GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);
    if(*comport==INVALID_HANDLE_VALUE)return -2;
 
    dcb.DCBlength=sizeof(DCB);
    if(!GetCommState(*comport,&dcb)){COMClose(comport);return -3;}
 
    dcb.BaudRate=baudrate;
    dcb.fBinary=TRUE;
    dcb.fOutxCtsFlow=FALSE;
    dcb.fOutxDsrFlow=FALSE;
    if(use_dtr==TRUE)dcb.fDtrControl=DTR_CONTROL_ENABLE;
    else dcb.fDtrControl=DTR_CONTROL_DISABLE;
    dcb.fDsrSensitivity=FALSE;
    dcb.fNull=FALSE;
    dcb.fRtsControl=RTS_CONTROL_DISABLE;
    dcb.fAbortOnError=FALSE;
    dcb.ByteSize=databits;
    dcb.Parity=parity;
    dcb.StopBits=stopbits;
    if(!SetCommState(*comport,&dcb)){COMClose(comport);return -4;}
 
    timeouts.ReadIntervalTimeout=0;
    timeouts.ReadTotalTimeoutMultiplier=0;
    timeouts.ReadTotalTimeoutConstant=read_wait_timeout;
    timeouts.WriteTotalTimeoutMultiplier=0;
    timeouts.WriteTotalTimeoutConstant=0;
    if(!SetCommTimeouts(*comport,&timeouts)){COMClose(comport);return -5;}
 
    SetupComm(*comport,2000,2000);
    PurgeComm(*comport,PURGE_RXCLEAR);
    if(use_dtr==TRUE)EscapeCommFunction(*comport,SETDTR);
    else EscapeCommFunction(*comport,CLRDTR);
 
    return 1;
}

int Measure_thread::COMClose(HANDLE * comport)
{
    if(*comport!=NULL)
    {
        if(CloseHandle(*comport)==0)return -1;
        *comport=0;
    }
    return 1;
}

int Measure_thread::SendCommandToGenerator(float amp,int freq)
{
    static unsigned long t;
    static unsigned char request[100];
 
    memset(request,0,sizeof(request));
    sprintf(request,"APPL:SIN %d HZ, %.4f VPP\r\n",freq,amp);
    PurgeComm(gen_port,PURGE_TXCLEAR);
    if(WriteFile(gen_port,request,strlen(request),&t,NULL)!=true)return GetLastError();
    return 1;
}

int Measure_thread::GetDataFromMultimeter(unsigned char * command,float coefficient,float * value)
{
    static unsigned long t;
    static unsigned char respond[100],log_text[200];
 
    memset(respond,0,sizeof(respond));
    PurgeComm(mm_port,PURGE_TXCLEAR);
    if(WriteFile(mm_port,command,strlen(command),&t,NULL)!=true)return GetLastError();
 
    if(ReadFile(mm_port,respond,17,&t,NULL)!=true)return GetLastError();
 
    //Заменяем точку на запятую
    for(t=0;t<strlen(respond);t++)
        if(respond[t]=='.')respond[t]=',';
    respond[15]=0;
    respond[16]=0;
    try{*value=coefficient*StrToFloat((String)((char*)(respond)));}
    catch(...){return -1;}
 
    return 1;
}