ADLINK DAQe-2214 - Manual (Page 58)

46 Operation Theory
Figure 4-11 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 pro-
grams. The DAQ-/DAQe-2213/2214 card software driver provides
simple settings for the scatter/gather function, including some
sample programs in the ADLINK All-in-One CD.
Figure 4-11: Scatter/gather DMA for Data Transfer
In non-chaining mode, the maximum DMA data transfer size is 2
M double words (8M bytes). However, there is no limitation on the
DMA data transfer size when using scatter/gather chaining mode.
You can also link the descriptor nodes circularly to achieve a multi-
buffered mode DMA.