Com Port C++ read 0xFF - c++

Question

I'm trying to read/write from a com port.
When I open the Com Port I make it Non overlapped.
Everything works fine, but when I read a 0xFF byte it sees it like an EOF and finishes the read.
Can I make a Non overlapped read 0xFF?
Here is my code:
//Opening the com port:
hComm = CreateFile( s.c_str(), // COM PORT
GENERIC_READ | GENERIC_WRITE, //
0, // exclusive access
NULL, // no security
OPEN_EXISTING, // must be a port
0 , // async i/o
NULL); //
//Port init:
void initPort(int baud)
{
uart_baud = baud;
DCB dcb;
dcb.DCBlength = sizeof(DCB);
GetCommState(hComm, &dcb); // read current config
dcb.BaudRate = baud;
dcb.ByteSize = 8;
dcb.StopBits = ONESTOPBIT;
dcb.Parity = NOPARITY;
dcb.fParity = FALSE;
SetCommState(hComm, &dcb);
}
//Reading:(PS: private: char rx_packet[1024]; int rx_size;)
int readByte(int timeout)
{
COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout = 1;
CommTimeOuts.ReadTotalTimeoutMultiplier = timeout;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 0;
SetCommTimeouts(hComm, &CommTimeOuts);
char byte;
DWORD bytes = 0;
if (ReadFile(hComm, &byte, 1, &bytes, NULL))
{
return bytes == 1 ? byte : -1;
}
return -1;
}
void readPacket(void)
{
int data_read;
bool first_read = true;
rx_size = 0;
DWORD dwEventMask;
DWORD ERR = 0;
if (!SetCommMask(hComm, EV_RXCHAR)) return;
if (!WaitCommEvent(hComm, &dwEventMask, NULL)) return;
while (rx_size < MAX_PACKET_SIZE)
{
data_read = readByte(first_read ? 200 : 50);
first_read = false;
if (data_read == -1)return;
rx_packet[rx_size] = (char)data_read;
rx_size++;
}
}
//Writing port:
bool writeByte(char byte)
{
DWORD bytes = 0;
WriteFile(hComm, &byte, 1, &bytes, NULL);
return bytes == 1 ? true : false;
}
void RvcCommUART::writePacket(BYTE *data , UINT16 size)
{
int tx_index = 0;
while (tx_index < size)
{
if (writeByte(data[tx_index]) == false) return;
tx_index++;
}
}

Answer 1

It seems that your char is signed (its signedness is implementation-dependent), so 0xFF is -1.
Use unsigned char to represent "bytes".