OpenCommPort function (winbase.h)

Attempts to open a communication device.

Syntax

HANDLE OpenCommPort(
  [in] ULONG uPortNumber,
  [in] DWORD dwDesiredAccess,
  [in] DWORD dwFlagsAndAttributes
);

[in] uPortNumber

A one-based port number for the communication device to open.

[in] dwDesiredAccess

The requested access to the device.

For more information about requested access, see CreateFile and Creating and Opening Files.

[in] dwFlagsAndAttributes

The requested flags and attributes to the device.

Note

For this function, only values of FILE_FLAG_OVERLAPPED or 0x0 are expected for this parameter.

Value	Meaning
FILE_FLAG_OVERLAPPED 0x40000000	The file or device is being opened or created for asynchronous I/O.

If the function succeeds, the function returns a valid HANDLE. Use CloseHandle to close that handle.

If an error occurs, the function returns INVALID_HANDLE_VALUE.

The uPortNumber parameter accepts one-based values. A value of 1 for uPortNumber causes this function to attempt to open COM1.

To support UWP, link against WindowsApp.lib.

Requirement	Value
Minimum supported client	Windows 10, version 1709 [desktop apps \| UWP apps]
Minimum supported server	Windows Server, version 1709 [desktop apps \| UWP apps]
Target Platform	Windows
Header	winbase.h (include Windows.h)
Library	OneCore.lib
DLL	KernelBase.dll