Continuous samples or N samples ?

[Danny5697]

Hi,

I am hoping to collect some vibration data (using accelerometers) from edge milling of a work-piece. For the set up of the DAQ assist, which type of acquisition mode would be most suitable (continuous or N sample?) . I plan on starting the data collection as the mill comes into contact with the work-piece and then press stop when the mill passes the work-piece. The data from that pass would then be saved for further analysis and the process would be repeated X amount of time. 

Due to covid-19, i am not able to enter the lab and test out which would be most suitable and so i am relying on literature online to help decide. 

[UliB]

Do you know N before the start of the acquisition?

I think the answer is no and therefore my advice is to use continuous.

[RavensFan · Accepted solution]

You want continuous.

It starts an acquisition, you may read X samples every iteration of your loop, but X+1 will be acquired immediately after on time, and will be available to read the next time you come around to read the next X samples.

With N samples, you'll read N samples.  The very next sample in time will get lost until you come around again to read the next N samples.  You are basically starting and stopping your acquisition with every read of N samples.  Those samples that would occur between the end of the last N and the start of the next N will never get acquired.  The two groups of N samples will be discontinuous with each other.

[Danny5697]

Ah makes sense, cheers!