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SetupComm (Compact 2013)

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3/28/2014

This function attempts to set the queue size values for a specified communications device.

Syntax

BOOL SetupComm(
  HANDLE hFile,
  DWORD dwInQueue,
  DWORD dwOutQueue
);

Parameters

  • hFile
    [in] Handle to the communications device returned by the CreateFile function.
  • dwInQueue
    [in] Specifies the recommended size, in bytes, of the device's internal input buffer.
  • dwOutQueue
    [in] Specifies the recommended size, in bytes, of the device's internal output buffer.

Return Value

Returns TRUE if the parameters are valid; otherwise FALSE.

Remarks

This function is optional. Queue size values are set at the platform dependent driver (PDD) level during initialization, and in most PDDs cannot be changed. This call may not actually do anything, depending on the driver implementation.

After a process uses the CreateFile function to open a handle to a communications device, it can call SetupComm to set the communications parameters for the device. If it does not set them, the device uses the parameters that were set during device initialization.

The dwInQueue and dwOutQueue parameters specify the recommended sizes for the internal buffers used by the driver for the specified device. For example, YMODEM protocol packets are slightly larger than 1024 bytes. Therefore, a recommended buffer size might be 1200 bytes for YMODEM communications.

The device driver receives the recommended buffer sizes, but is free to use any I/O buffering scheme as long as it provides reasonable performance and data is not lost due to overrun (except under extreme circumstances).

For example, the function can succeed even though the driver does not allocate a buffer, as long as some other portion of the system provides equivalent functionality.

Requirements

Header

winbase.h

Library

Serdev.lib

See Also

Reference

Serial Communications Functions
SetCommState

Other Resources

CreateFile