The file input and output (I/O) functions (CreateFile, CloseHandle, ReadFile, ReadFileEx, WriteFile, and WriteFileEx) provide the basic interface for opening and closing a communications resource handle and for performing read and write operations. The Microsoft® Win32® application programming interface (API) also includes a set of communications functions that provide access to communications resources. This overview describes the use of file I/O and communications functions, which enable applications to perform the following tasks:
·Open a handle to a specified communications resource.
·Set and query the configuration of a serial communications resource.
·Read from or write to a serial communications resource.
·Monitor a specified set of events that might occur for a given serial communications resource.
·Send a control command to the device driver associated with a specified communications resource, causing the driver to execute an extended function.