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Chapter 3 Hardware Overview
DIO 6533 User Manual 3-14 © National Instruments Corporation
• Direct-memory access (DMA) transfers are faster than
interrupt-driven transfers, especially for pattern generation. By
default, the software uses DMA if available.
♦ The PCI-DIO-32HS always supports DMA transfers.
♦ The PXI-6533 supports DMA if inserted into a peripheral slot that
allows bus arbitration (bus mastering). When using a slot that does
not allow bus arbitration, use software to select interrupt-driven
transfers.
♦ The AT-DIO-32HS supports DMA, if system DMA resources are
available. If a second DMA channel is available, you can
minimize channel reprogramming time by allocating two DMA
channels to a single transfer. By allocating two channels, you
allow the AT-DIO-32HS software to reprogram one channel
while continuing transfers on the other channel. This is
particularly important for pattern generation.
♦ The DAQCard-6533 cannot be programmed for DMA.
• The average bus bandwidth is higher for the PCI-DIO-32HS or
PXI-6533 than for the AT-DIO-32HS, and higher for the
AT-DIO-32HS than for the DAQCard-6533.