ADLINK DAQe-2006 - Manual (Page 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.