SetCommMask

SetCommMask ()函数设置事件掩模来监视指定通信端口上的事件，其原型为：

BOOL SetCommMask(
　HANDLE hFile, //标识通信端口的句柄
　DWORD dwEvtMask //能够使能的通信事件
);
　　串口上可能发生的事件如下表所示：

值 事件描述EV_BREAKA break was detected on input.EV_CTS The CTS (clear-to-send) signal changed state.EV_DSRThe DSR(data-set-ready) signal changed state.EV_ERRA line-status error occurred. Line-status errors are CE_FRAME, CE_OVERRUN, and CE_RXPARITY.EV_RING A ring indicator was detected.EV_RLSD The RLSD (receive-line-signal-detect) signal changed state.EV_RXCHARA character was received and placed in the input buffer.EV_RXFLAG The event character was received and placed in the input buffer. The event character is specified in the device's DCB structure, which is applied to a serial port by using the SetCommState function.EV_TXEMPTYThe last character in the output buffer was sent.