Keithley KPCI-3101 Series, User Manual

Page: 31 / 146

KPCI-3101 — KPCI-3104 Series User’s Manual Principles of Operation 2-11
Figure 2-2
Continuous post-trigger mode without triggered scan
Figure 2-3 illustrates the same example using triggered scan mode (either internally or exter-
nally retriggered). The multiscan count is 2, indicating that the channel-gain list will be scanned
twice per trigger or retrigger. In this example, post-trigger analog input data is acquired on each
clock pulse of the A/D sample clock until the channel-gain list has been scanned twice; then, the
board waits for the retrigger event. When the retrigger event occurs, the board scans the channel-
gain list twice more, acquiring data on each pulse of the A/D sample clock. The process repeats
continuously with every specified retrigger event.
Figure 2-3
Continuous post-trigger mode with triggered scan
Pre-Trigger acquisition
Use pre-trigger acquisition mode (continuous pre-trigger mode) when you want to acquire data
before a specific external event occurs.
Using software, specify:
• The dataflow as continuous pre-trigger
•
The pre-trigger source as the software trigger
• The post-trigger source as the external digital (TTL) trigger
•
The retrigger mode as the internal retrigger (if you are using triggered scan mode)
Refer to page 2-7 for more information on the supported conversion modes; refer to page 2-10
for information on the supported trigger sources.
NOTE
When using pre-trigger acquisition, you cannot use externally-
retriggered scan mode; refer to
page 2-8 for more information on
triggered scan mode.
Post-trigger event occurs.
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
Chan 0
Chan 1
Chan 2
Chan 0
Chan 1
Chan 2
A/D
Sample
Clock
Post-trigger data acquired
continuously.
Post-trigger event occurs;
post-trigger data acquired for
two scans of the CGL.
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
A/D
Sample
Clock
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
Retrigger event occurs;
post-trigger data acquired for
two scans of the CGL.
Board waits for
retrigger event.