Adlink DAQe-2006 Bedienungsanleitung PDF herunterladen (Seite 58)

46 Operation Theory

list for the input DMA channel or the output DMA channel.

Figure 4-13 shows a linked list that is constructed by three

DMA descriptors. Each descriptor contains a PCI address, a

local address, a transfer size, and the pointer to the next

descriptor. You can allocate many small size memory blocks

and chain their associative DMA descriptors altogether by their

application programs. The DAQ-/DAQe-/PXI-2016/2010/2006/

2005 card software driver provides simple settings for the scat-

ter/gather function, including some sample programs in the

ADLINK All-in-One CD.

Figure 4-13: Scatter/gather DMA for data transfer

In non-chaining mode, the maximum DMA data transfer size is 2

M double words (8M bytes). However, by using chaining mode,

scatter/gather, there is no limitation on the DMA data transfer size.

You can also link the descriptor nodes circularly to achieve a multi-

buffered mode DMA.

1 2 ... 53 54 55 56 57 58 59 60 61 62 63 ... 91 92

Keine Kommentare

Adlink DAQe-2006 Bedienungsanleitung Seite 58