Advantech iDAQ-731, User Manual

Page: 34 / 54

iDAQ-731_751_763D User Manual 24
3.4 Configuration for Buffered Digital Input
Acquisition
According to software configurations, buffered digital input acquisition can be classi -
fied into two types:

One-buffered digital input acquisition

Streaming digital input acquisition
3.4.1 One-buffered Digital Input Acquisition
For one-buffered acquisition, only a specified number of samples is acquired. The
start or stop of acquisition can be controlled by a software command or a hardware
signal. Three types of acquisitions can be achieved: post-trigger acquisition, pre-trig -
ger acquisition, and about-trigger acquisition.
3.4.1.1 Post-Trigger Acquisition
A post-trigger acquisition acquires a specified number of samples after the start trig -
ger. The acquisition starts when a start trigger is received and automatically stops
when the specified number of samples is acquired. An example of 5-sample post-trig -
ger acquisition is shown in Figure 3.10.
Figure 3.10 Post-trigger acquisition.
The start trigger can be a software command or a hardware signal. If a hardware sig -
nal is used as the start trigger, the start of acquisition can be delayed for a specified
number of sample clock cycles after a start trigger is received. Figure 3.11 shows an
example of a 2-sample delay post-trigger acquisition. Refer to the device specifica -
tions for possible signal sources.
Figure 3.11 Post-trigger acquisition with delay.