Communications Errors

There are other circumstances where a read or write operation can be completed with fewer than the requested number of characters, even though a time-out has not occurred. Following are some examples:

• Some drivers support the use of special characters, which complete a read operation immediately with only the characters that have been read up to the point when they are received.
• The PurgeComm function can be called to prematurely terminate pending read or write operations. This function can also delete the contents of the output or input buffers, or both.
• If a communications error occurs during a read or write operation, all I/O operations on the communications resource are terminated. Break conditions, parity errors, or framing errors are examples of such errors. When an error occurs, the process must call the ClearCommError function to clear the error flag before it can begin additional I/O operations. ClearCommError reports the specific error that occurred and the current status of the device.