The communications driver exports the CommWriteString and EnableNotification functions. The CommWriteString function writes a string of one or more bytes to the given communications device.
The EnableNotification function enables or disables port status notifica-tions. If notifications are enabled, the communications driver posts a WM_COMMNOTIFY message to a given window on certain events. This eliminates the need for communications applications to set timers and use the GetCommError, GetCommEventMask, and SetCommEventMask func-tions to monitor port status changes.