A SERCX2SYSTEMDMATRANSMIT object handle is an opaque reference to a system-DMA-transmit object in version 2 of the serial framework extension (SerCx2).


The SerCx2SystemDmaTransmitCreate method creates a system-DMA-transmit object. SerCx2 uses this object to manage system DMA transactions that write data to the serial controller. This object is opaque to serial controller drivers. SerCx2SystemDmaTransmitCreate supplies, as an output parameter, a SERCX2SYSTEMDMATRANSMIT handle to the newly created system-DMA-transmit object. SerCx2 and the serial controller driver use this handle to refer to the object in subsequent system-DMA-transmit transactions. For more information, see SerCx2 System-DMA-Transmit Transactions.

After SerCx2SystemDmaTransmitCreate creates the system-DMA-transmit object, this object exists for the lifetime of the framework device object that represents the serial controller device. The system-DMA-transmit object is automatically deleted when the device object is deleted. The serial controller driver must not try to delete the system-DMA-transmit object by calling a method such as WdfObjectDelete.

A serial controller driver can, as an option, create a system-DMA-transmit object, but can create no more than one such object. The driver can create this object only under the following conditions:

  • The driver previously created a PIO-transmit object.
  • The driver has not created a custom-transmit object.

For more information about PIO-transmit objects, see SERCX2PIOTRANSMIT. For more information about custom-transmit objects, see SERCX2CUSTOMTRANSMIT.




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