Data Translation DT300 Series, Руководство пользователя, Страница: 85 / 164

Principles of Operation
85
Figure 29: Continuous About-Trigger Mode
Figure 30 illustrates the same example using software-retriggered scan mode. The multiscan
count is 2, indicating that the channel list will be scanned twice per trigger or retrigger. In this
example, pre-trigger analog input data is acquired on each clock pulse of the A/D sample
clock for two scans; then, the board waits for the software retrigger event.
When the software retrigger occurs, the board begins acquiring pre-trigger data until the
post-trigger event occurs. Then, the board finishes scanning the channel list the specified
number of times, acquiring the data as post-trigger samples. On all subsequent software
retriggers, post-trigger data is acquired.
Figure 30: Continuous About-Trigger Mode with Triggered Scan
Pre-trigger event occurs
Chan 0
Chan 1
Chan 0
. . .
A/D
Sample
Clock
Post-trigger event
Pre-trigger data acquired
Post-trigger data acquired
Chan 1
Chan 0
Chan 1
Chan 0
Chan 1
Chan 0
Chan 1
Chan 0
Chan 1
Pre-trigger event occurs;
pre-trigger data is
acquired for 2 scans of
the CGL.
Chan 0
Chan 1
Chan 0
Chan 1
A/D Sample
Clock
Re-trigger event occurs;
pre-trigger data is
acquired until
post-trigger occurs.
Chan 0
Chan 1
Chan 0
Chan 1
Chan 0
Chan 1
Post-trigger event
occurs; post-trigger data
is acquired until the end
of the number of scans.
Retrigger event
occurs; post-trigger
data is acquired for
2 scans of the
CGL.
Chan 0
Ch1