Chapter 9
Bus Interface
©
National Instruments Corporation
9-3
Changing Data Transfer Methods between DMA and IRQ
There are a limited number of DMA channels per device. Refer to
Appendix A,
, for the specifications document
for your device. Each operation (for example, AI, AO, and so on) that
requires a DMA channel uses that method until all of the DMA channels
are used. Once all of the DMA channels are used, you will get an error if
you try to run another operation requesting a DMA channel. If appropriate,
you can change one of the operations to use interrupts. For NI-DAQmx, use
the
Data Transfer Mechanism
property node. For Traditional NI-DAQ
(Legacy), use the
Set DAQ Device Information VI
or function.