22
Operation Theory
formed after the trigger signal is specified by the PSC_counter,
as illustrated in Figure 4.1.2. The total acquired data length =
(number_of_channels_enabled_for _scan_acquisition) *
PSC_counter.
Delay Trigger Acquisition
Use delay trigger when users want to delay the scan after a
trigger signal. The delay time is determined by the
Delay_counter, as shown in Figure 4-3.
The counter counts down on the rising edges of Delay_counter
clock source after the trigger signal. When the count reaches
0, DAQ/PXI-2500 SERIES starts to perform the scan. The
acquired data length = (num-
ber_of_channels_enabled_for_scan_acquisition) *
PSC_counter. The Delay_counter clock source can be soft-
ware selected from Internal 40MHz Timebase, external input
(AFI-1), or General Purpose Timer/Counter Output 0/1.
Post-Trigger or Delay-trigger Acquisition with retrigger
Use post-trigger or delay-trigger acquisition with retrigger when
users want to perform repeated scans with respect to the
repeated triggers. Figure 4-4 illustrates an example. Two scans
are performed after the first trigger signal, and then wait for the
next trigger signal. When the trigger signal occurs, it performs
2 more scans.
When retrigger function is disabled, only one trigger signal
would be accepted after retrigger
Note
: Retrigger signals asserted during scan process will be ignored.
