National Instruments PCI-6281, Руководство пользователя

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Bus Interface
The bus interface circuitry of M Series devices efficiently moves data between host memory and
the measurement and acquisition circuits. M Series devices are available for the following
platforms:
• PCI
• PCI Express
• PXI
• PXI Express
• USB
All M Series devices are jumperless for complete plug-and-play operation. The operating
system automatically assigns the base address, interrupt levels, and other resources.
NI M Series PCI/PCIe/PXI/PXIe devices incorporate PCI-MITE technology to implement a
high-performance PCI interface. M Series USB devices incorporate USB-STC2 technology to
implement a Hi-Speed USB interface.
Data Transfer Methods
Refer to the following sections for information about bus interface data transfer methods for
M Series devices.
PCI/PCI Express Device and PXI/PXI Express Module
Data Transfer Methods
The primary ways to transfer data across the PCI bus are as follows:
•
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, PCI Express, PXI, and PXI Express devices and modules.
NI M Series PCI/PCIe/PXI/PXIe devices have six 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