Reading from a Serial Port (Windows CE 5.0)

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An application calls the ReadFile function to receive data from a device at the other end of a serial connection.

ReadFile takes the same parameters as the WriteFile function.

Typically, a read operation is a separate thread that is always ready to process data arriving at a serial port. A communication event signals the read thread that there is data to read at a serial port. Then the read thread waits for another communication event.

Typically, an application waits for an EV_RXCHAR and then reads (with a very short timeout) all data that is available.

For more information about communication events, see Using Communication Events.

To read from a serial port

1. Pass the port handle to ReadFile in the hFile parameter.

   The CreateFile function returns this handle when an application opens a port.

2. Specify a pointer to receive the data that is read in lpBuffer.

3. Specify the number of characters to read in nNumberOfBytesToRead.

4. Specify a pointer to a location where ReadFile will store the number of bytes read in lpNumberOfBytesRead.

5. Be sure that lpOverlapped is NULL.

   Windows CE does not support overlapped I/O.

The following code example shows how to receive data using the ReadFile function.

BYTE Byte;
DWORD dwBytesTransferred;

ReadFile (hPort,                // Port handle
          &Byte,                // Pointer to data to read
          1,                    // Number of bytes to read
          &dwBytesTransferred,  // Pointer to number of bytes
                                // read
          NULL                  // Must be NULL for Windows CE
);

See Also

Programming Serial Connections

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