Measurement Computing Data Translation DT3034, User Manual, Page: 82 / 178

Principles of Operation
81
Trigger Acquisition Modes
DT3034 boards can acquire data in post-trigger mode, pre-trigger mode, or about-trigger
mode. These trigger acquisition modes are described in more detail in the following
subsections.
Post-Trigger Acquisition
Use post-trigger acquisition mode when you want to acquire data when a post-trigger or
retrigger, if using triggered scan mode, occurs.
Using software, specify the following parameters:
• The dataflow as Continuous.
• The trigger source to start the post-trigger acquisition (the post-trigger source) as any of
the supported trigger sources.
Refer to page 76 for more information on the supported conversion modes; refer to page 79 for
information on the supported trigger sources.
Post-trigger acquisition starts when the board detects the post-trigger event and stops when
the specified number of post-trigger samples has been acquired or when you stop the
operation.
If you are using triggered scan mode, the board continues to acquire post-trigger data using
the specified retrigger source to clock the operation. Refer to
page 77 for more information on
triggered scan mode.
Figure 22 illustrates continuous post-trigger mode using a channel list with three entries:
channel 0, channel 1, and channel 2. Triggered scan mode is disabled. In this example,
post-trigger analog input data is acquired on each clock pulse of the A/D sample clock. The
board wraps to the beginning of the channel list and repeats continuously
(continuously-paced scan mode).
Figure 22: Continuous Post-Trigger Mode without Triggered Scan
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