How do I determine the fastest data acquisition speed (Hz) a user can select in program?

[uscmagz]

I am using Labview 6.1.

I slightly modified Simple Data Logger.vi (took out the 200ms small loop delay, etc). I am setting up a data acquisition program where up to 8 channels are read at once. I can't figure out the maximum scan rate, though. I don't want a user to put in 100Hz if the program can't keep up with 100Hz. How can I determine this maximum rate?

Just testing on my own entering 100Hz,acquiring, and then looking at the recorded spreadsheet data, I don't see 100 data points per second. I think it's more like 50Hz as a maximum.

Suggestions are appreciated, and if I need to post an example of what I'm talking about, I will.

[Herbert Engels]

Execute acquisition and file storage in a sequence and take a time stamp before and after. For a given number of scans, this will give you the time consumption, so you can calculate the scan rate. A while loop that counts the scans and times out after a second is almost as accurate as that.

[SVences]

Hello!

The main factor that determines how fast you can acquire is the type of data acquisition board that you have. In the user�s manual of your board, under the specifications section, the maximum sample rate is listed and you cannot go any faster than that.

Once you have written your data acquisition program, its size also determines how fast you can acquire, because time is needed for every function in your program to be executed. Keep in mind that this is system dependant (processor speed, memory, etc.). You can benchmark your program as Herbert suggested. I am including some links that can help you do this.

How do you determine if you are acquiring data
too fast or doing too much processing during a contin...

Benchmarking Multiple E-Series or PCI S-Series Boards and Writing to Disk

Hope this helps!

Sylvia V
Applications Engineer
National Instruments