National Instruments 653X User Manual page 117

Appendix E Optimizing Your Transfer Rates
Obtaining the Fastest Transfer Rates
Table E-2. Devices That Support Direct-Memory Access (DMA) Transfers
Device
AT-DIO-32HS
DAQCard-6533 for
PCMCIA
PCI-DIO-32HS
PCI-6534
PXI-6533
PXI-6534
653X User Manual
Table E-1. Peak Transfer Rates Based on Mode and Protocol Used (Continued)
Mode/Protocol
Handshaking Trailing-Edge Pulse
Handshaking Burst
Pattern I/O
To achieve the highest transfer rates possible, consider the following:
• Burst mode is the fastest handshaking protocol. You can further
increase speed by using short cables.
• Minimize the number of other I/O devices active in the system. Your
system bus should be as free as possible from unrelated activity.
• Use the 6534 devices, which have onboard memory. If you are using a
6533 device, you can connect it to an external FIFO using the burst
handshaking protocol and clock data out of the FIFO to the peripheral
device.
• Direct-memory access (DMA) transfers are faster than interrupt-driven
transfers, especially for pattern I/O. Refer to Table E-2 to determine
whether your device supports DMA transfers. If DMA transfers are
available, the software will use it by default.
Supported if system DMA resources available. If you are using
two DMA channels, data transfer is faster.
Not supported
Supported
Supported if device is in a peripheral slot that allows bus arbitration
(bus mastering). Otherwise, use software to select interrupt-driven
transfers. PXI chassis have bus arbitration for all slots.
Direct-Memory Access
E-2
Peak Rate (MS/s)
1.8
20
20
ni.com