LabView sampling rate

[Guohua Jing]

I use the LabView6 and DAQ6533(PCMCIA) to acquire some data. However, it
seems the sampling rate can't
reach even 4kHz, otherwise my program will down.

My code is almost the same as the Example "continuous handshaking input.vi"
provide by LabView6, my modification
is that I add an "build array.vi" and "shift register" in the while loop in
the example because I need to output the data
together, another modification is that I configure the DAQ card according to
my hardware connection.

Does anyone have similar problem? or If you have a good advice on relative
high-speed sampling in LabView, please
tell me.

Thanks.

GH

[Christopher Mitchell]

The DAQ6533 card should be able to handle the 4kHz sampling rate without any problems. My concern is the 'Build Array' in the While Loop. If you are sampling a small amount of data this should not be a problem. If you are sampling large amounts of data, the 'Build Array' function has to find a new chunck of memory and copy the data from the old memory location to the new memory location every time it is used. Over time this can slow down your VI. My suggestion would be to initialize an array outside of the While Loop, and then use the 'Replace Array Subset' inside the loop so that you can place your data in the array. As before, you will still need to use a shift register so that you have access to the array from iteration to iteration.

Hope this helps
.