I Got Solution from other post in Multifunctional DAQ Forum which is as follows :-
Attached is a VI that should do what you're
asking for. I'll try to explain what the program is doing since it
requires you to override a lot of the default behaviors in the driver.
Also, the DAQ device you are using doesn't support a true "stop" trigger so I'm using a reference trigger to get as close to the desired functionality as possible.
First, the program configures a finite acquisition that uses both a start trigger and a reference trigger. The acquisition is using the onboard sample clock and will acquire 4 samples (2 pre-trigger samples and 2 post-trigger samples). Four may seem like an odd number here, but it allows us to emulate the functionality of a stop trigger as close as possible. Given this configuration, you must acquire at least 2 samples before the "stop" trigger is recognized, and you must acquire 2 more samples after the "stop" trigger is recognized. Hopefully this restriction is acceptable. You can always discard the last two data points after the stop trigger
if they're not of interest, but you're stuck always acquiring at least
two points between when the start and stop triggers are recognized.
The
program also overrides the default buffer size and read position. By
default, the DAQmx driver will pick a buffer size exactly big enough to
fit the pre-trigger and post-trigger data (4 samples in this case) and will begin reading data from the start of the pre-trigger
data. Explicitly allocating a larger buffer will allow your acquisition
to execute without receiving buffer overflow errors, and changing the
default read position will allow you to read all of the data between
the start and stop triggers as it is acquired and not just the pre-trigger and post-trigger data.
Finally,
the while loop takes care of reading the data. In this case, the loop
continues to read data until the task is done and there are no longer
samples available for reading from the buffer. The number of samples
read per iteration is the lesser of the user specified amount or the
number of samples available for reading from the buffer.
I hope this helps. Good luck.
BY-
reddog
Proven Veteran
