Keithley KPCI-3110, Руководство пользователя

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KPCI-3110 and KPCI-3116 User’s Manual Functional Description 2-13
Figure 2-5
Continuous pre-trigger mode
Figure 2-6 illustrates the same example using internally-retriggered triggered scan mode. The
multiscan count is 2 indicating that the channel-gain 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 until the channel-gain list has been scanned twice; then, the board waits for
the internal retrigger event. When the internal retrigger occurs, the process repeats. The process
stops when the post-trigger event occurs.
Figure 2-6
Continuous pre-trigger mode with triggered scan
About-trigger acquisition
Use about-trigger acquisition mode (continuous about-trigger mode) when you want to acquire
data both before and after a specific external event occurs. This operation is equivalent to doing
both a pre-trigger and a post-trigger acquisition.
Using software, specify the following parameters:
•
The dataflow as continuous about-trigger
• The pre-trigger source as the software trigger
•
The post-trigger source as the external digital (TTL) trigger or the external analog threshold
trigger
• If you are using triggered scan mode, the retrigger mode as the internal retrigger
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.
When using about-trigger acquisition, you cannot use an external retrigger in triggered scan
mode. Refer to
page 2-8 for more information on triggered scan mode.
Pre-trigger Event Occurs
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
A/D
Sample
Post-trigger Event Occurs
Chan 0
Pre-trigger Data Acquired
Acquisition Stops
Pre-trigger event occurs;
pre-trigger data is acquired
for two scans of the CGL.
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
A/D
Sample
Chan 0
Chan 1
Chan 2 Chan 0
Retrigger event occurs;
pre-trigger data is
acquired until post-trigger
event occurs.
Board waits for
retrigger event.
Post-trigger event
occurs; acquisition
stops.