ASYNC SETBAUDRATE (41h)

This function sets the bit rate.
 * Category: IOCTL_ASYNC (01h)
 * Function: ASYNC_SETBAUDRATE (41h)

Parameter Packet Format
Field       Length     C Datatype Bit Rate    WORD       USHORT

Data Packet Format
None. Packet pointer must be NULL.

Returns
If the call is made with invalid Parameter Packet values or an invalid Data Packet pointer, a general failure error is reported.

Remarks
If a general failure error is not returned, the physical device driver performs the action described in the Bit Rate field. An OPEN request packet does not cause the physical device driver to change the bit rate from its previous value. The initial value is 1200 bps.

The COM device hardware determines which bit rates can be supported on a given system. The range of bit rates supported by Function 41h is 2 bps to 19200 bps for COM ports on conventional serial devices. For COM ports on enhanced serial devices, the range is 10 bps to 57600 bps. A call with a value beyond this range fails with the ERROR_INVALID_PARAMETER return code.