National Instruments DAQ X Series, Руководство пользователя

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© National Instruments 10-1 X Series User Manual
10
Bus Interface
The b u s interface circ u itry of X Series devices efficiently moves data
between host memory and the meas u rement and acq u isition circ u its.
X Series devices are available for the following platforms:
• PCI Express
• PXI Express
• USB
Data Transfer Methods
Refer to the following sections for information abo u t b u s interface data
transfer methods for X Series devices.
PCI Express/PXI Express Device Data Transfer Methods
The primary ways to transfer data across the PCI Express b u s are as
follows:
• Direct Memory Access (DMA) —DMA is a method to transfer data
between the device and comp u ter memory witho u t the involvement of
the CPU. This method makes DMA the fastest available data transfer
method. NI
u ses DMA hardware and software technology to achieve
high thro u ghp u t rates and increase system u tilization. DMA is the
defa u lt method of data transfer for PCI Express and PXI Express
devices.
NI PCI Express X Series and PXI Express devices have
eight f
u lly-independent DMA controllers for high-performance
transfers of data blocks. One DMA controller is available for each
meas
u rement and acq u isition block:
– Analog inp u t
– Analog o u tp u t
– Co u nter 0
– Co u nter 1
– Co u nter 2
– Co u nter 3
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