Changing Data Transfer Methods - National Instruments NI 6221 User Manual

Changing Data Transfer Methods

© National Instruments Corporation
operations. Refer to the
Chapter 5, Analog
(NI PCI/PCIe/PXI/PXIe Devices)
M Series devices, each measurement and acquisition circuit (that is, AI,
AO, and so on) has a dedicated DMA channel. So in most applications, all
data transfers use DMA.
However, NI-DAQmx allows you to disable DMA and use interrupts. To
change your data transfer mechanism between DMA and interrupts in
NI-DAQmx, use the Data Transfer Mechanism property node.
USB M Series devices have four dedicated USB Signal
(USB Devices)
Stream channels. These channels are assigned to the first four
measurement/acquisition circuits that request one. If a USB Signal Stream
is not available, you must set the data transfer mechanism to programmed
I/O; otherwise the driver returns an error. To change your data transfer
mechanism between USB Signal Stream and programmed I/O, use the
Data Transfer Mechanism property node function in NI-DAQmx.
Software-Timed Generations
Output, for more information.
On PCI, PCI Express, PXI, and PXI Express
10-5
Chapter 10 Bus Interface
section of
M Series User Manual