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Operation Theory
Post-Trigger or Delay-Trigger with Re-trigger
Use post-trigger or delay-trigger with re-trigger function when you want to
generate waveform after more than one trigger events. The re-trigger
function can be enabled or disabled by software setting. In figure 23, each
trigger signal will initiate a waveform generation. However, the trigger
event would be ignored while the waveform generation is ongoing.
(UC _Counter=4, IC_Counter=2)
4 update counts, 2 iterations
Ignored
DAWR
WFG_in_progress
Operation start
Trigger
Output Waveform
Call software stop
function to terminate
retrigger mode
waveform generation
Figure 23: Re-triggered waveform generation (Assuming the data in
the data buffer are 2V, 4V, 2V, 0V)
4.2.2.2 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 itera-
tions can be finite (Figure 24) or infinite (Figure 25).
A data FIFO on board is used to buffer the digital data for DA output. If the
data size of a single waveform you specified (That is, Update Counts in
UC_counter) is less than the FIFO size, after initially 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 won’t occupy the PCI bandwidth when repetitive waveforms
are performed. 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 DAQ/PXI-2010 is 2k samples and on
DAQ/PXI-2005/2006 it is 512 samples.
