Advantech PCIE-1841 User Manual page 29

3.5.1.2 Pre-trigger acquisition
A pre-trigger acquisition acquires a specified number of samples before the stop trig-
ger. The acquisition is started by a software command and stops when a hardware
stop trigger is received. Figure 3.12 shows an example of a 5-sample pre-trigger
acquisition. Only the samples in the shaded area are returned.
The stop trigger can only be a hardware signal. Refer to the device specifications for
possible signal sources.
3.5.1.3 About-trigger acquisition
An about-trigger acquisition is the same as a pre-trigger acquisition except that the
time when the acquisition stops can be delayed by a specified number of sample
clock cycles. Figure 3.13 shows an example of a 5-sample about-trigger acquisition
with 2 cycles of stop delay. Only the samples in the shaded area are returned.
The stop trigger can only be a hardware signal. Refer to the device specifications for
possible signal sources.
Figure 3.12 Pre-trigger acquisition
Figure 3.13 About-trigger acquisition
21 PCIE-1841 User Manual