COM端口C++讀取0xFF

我試圖從COM端口讀取/寫入。當我打開Com端口時，我使它不重疊。一切工作正常，但是當我讀取0xFF字節它看起來像EOF並完成讀取。我可以做一個非重疊讀取0xFF嗎？COM端口C++讀取0xFF

這裏是我的代碼：

 

//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++; 
    } 
}

來源

2017-03-21 dorin.petre

看來你char簽署（其符號性是實現相關的），所以0xFF是-1。使用表示「字節」。

來源

2017-03-21 15:54:51 molbdnilo

在FileRead函數中字節是接收字節，字節數是函數正在讀取的字節數......這是將它用作DWORD的方式;它讀取它的字節的值發送到readPacket –

這是問題，它工作時，我確實從char字節更改爲unsigned char字節，非常感謝你 –

COM端口C++讀取0xFF

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