ADLINK DAQe-2214 - Manual (Page 65)

Operation Theory 53
Iterative Waveform Generation
Set IC_Counter in order to generate iterative waveforms from the
data of a single waveform. The counter stores the iteration number
and the iterations may be finite (Figure 4-16) or infinite (Figure 4-
17). Take note that in infinite mode the waveform generation does
not stop until software stop function is executed and IC_Counter is
still valid when stop mode III is selected. Both figures assume that
the data in the data buffer are 2V, 4V, 2V, and 0V.
An onboard data FIFO is used to buffer the digital data for DA out-
put. If the data size of a single waveform you specified (That is,
Update Counts in UC_counter) is less than the FIFO size, after ini-
tially transferring the data from the host PC memory to the FIFO
on board, the data in the FIFO will be automatically re-transmitted
whenever a single waveform is completed. Therefore, it does not
occupy the PCI bandwidth when repetitive waveforms are per-
formed. However, if the size of a single waveform were larger than
that of the FIFO, it needs to be intermittently loaded from the host
PC’s memory via DMA, when a repetitive waveforms is performed
thus PCI bandwidth would be occupied.
The data FIFO size on the DAQ-/DAQe-2214 card is 1024 (words)
when one DA channel is enabled, or 512 (words) when both DA
channels are enabled.
Figure 4-16: Finite Iterative Waveform Generation with Post-trigger
(DLY2_Counter = 0)