Bus Interface; Data Transfer Methods; Pci Express/Pxi Express Device Data Transfer Methods - National Instruments DAQ X Series User Manual

Bus Interface

The bus interface circuitry of X Series devices efficiently moves data
between host memory and the measurement and acquisition circuits.
X Series devices are available for the following platforms:
•
•
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Data Transfer Methods

Refer to the following sections for information about bus 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 bus are as
follows:
•
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PCI Express
PXI Express
USB
Direct Memory Access (DMA)—DMA is a method to transfer data
between the device and computer memory without the involvement of
the CPU. This method makes DMA the fastest available data transfer
method. NI uses DMA hardware and software technology to achieve
high throughput rates and increase system utilization. DMA is the
default method of data transfer for PCI Express and PXI Express
devices.
NI PCI Express X Series and PXI Express devices have
eight fully-independent DMA controllers for high-performance
transfers of data blocks. One DMA controller is available for each
measurement and acquisition block:
– Analog input
– Analog output
– Counter 0
– Counter 1
– Counter 2
– Counter 3
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X Series User Manual