我在Windows上使用ReadFile()
從串口讀取數據。這段代碼在某個時間點工作正常,但現在失敗了,我試圖找出問題的根源,所以我懷疑這是串行配置或超時問題,因爲沒有任何變化。ReadFile()表示失敗,但錯誤代碼爲ERROR_SUCCESS
ReadFile()
返回false,表示發生錯誤。但是,當我立即檢查GetLastError()
的值時,它返回0,即ERROR_SUCCESS
。讀取的字節數是0,所以我傾向於認爲確實有出錯了,但那個錯誤代碼完全沒用。
任何想法?謝謝。
編輯:這裏有一些相關的代碼片段:
#define GPS_COM_PORT L"COM3"
// for reference, the device communicates at 115200 baud,
// no parity, 1 stop bit, no flow control
// open gps com port
hGpsUart = CreateFile(GPS_COM_PORT, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if (hGpsUart == INVALID_HANDLE_VALUE)
{
if (GetLastError() == ERROR_FILE_NOT_FOUND)
{
msg.setText("GPS COM port does not exist!");
msg.exec();
QApplication::quit();
}
msg.setText("Error occurred while trying to open GPS COM port!");
msg.exec();
QApplication::quit();
}
// set gps com port settings
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
if (!GetCommState(hGpsUart, &dcbSerialParams))
{
msg.setText("Could not get GPS COM port settings!");
msg.exec();
QApplication::quit();
}
dcbSerialParams.BaudRate = CBR_115200;
dcbSerialParams.ByteSize = 8;
dcbSerialParams.StopBits = ONESTOPBIT;
dcbSerialParams.Parity = NOPARITY;
if (!SetCommState(hGpsUart, &dcbSerialParams))
{
msg.setText("Could not set GPS COM port settings!");
msg.exec();
QApplication::quit();
}
// set gps com port timeouts
timeouts.ReadIntervalTimeout = MAXDWORD;
timeouts.ReadTotalTimeoutConstant = 0;
timeouts.ReadTotalTimeoutMultiplier = 0;
timeouts.WriteTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 10;
if (!SetCommTimeouts(hGpsUart, &timeouts))
{
msg.setText("Could not set GPS COM port timeouts!");
msg.exec();
QApplication::quit();
}
// ... later in the code ...
char buf[161] = {0};
DWORD bytes_read = 0;
// This returns false...
if (!ReadFile(hGpsUart, buf, 160, &bytes_read, NULL))
{
// Yet in here, GetLastError() returns ERROR_SUCCESS (0)
QMessageBox msg;
msg.setText("Error reading from GPS UART!");
msg.exec();
}
你能發表一些你的代碼嗎? – 2011-04-16 07:45:35
已發佈。感謝您的關注! – 2011-04-16 07:59:37
不知道的人,對不起 – 2011-04-16 08:11:02