Continuous acquisition of data for 24 H switching to periodic acquisition for 24 H with time delay

[aadrienne]

I am a new user to Labview and I have been using a simple program to acquire data from two IN DAQ boards with a timing delay between acquisition periods. However, I'd like to acquire data for 24 hours before switching to collecting data at set intervals of time and I'd like to obtain all of that data within the same output file and graphs. I have played around with different case structures and loops and cannot figure out how to alter the periods of time for acquisition. If anyone has any pointers that would be greatly appreciated. I have attached my Vi.

[camerond]

I have no idea what you mean by "continuous" and "periodic" data acquisition. Surely you don't mean that at first you are going to acquire data at time points differing by 0 nsec (the physicists say that even time is quantized, not continuous). You just mean that you want to take data quickly at first, then more slowly, right?

Then you just need to change your acquisition rate after X number of samples, or X amount of elapsed time, however you want to figure it. Put your for loop inside a while loop (or another for loop) which would set the number of samples to take at what rate for each different time slice.

Well, in order to do that and record the data on the same visual representation, I would not use a chart, but a graph because for a chart your X axis is incremented by a constant each data point, and in a graph you can put actual time (or other) X axis values for individual data points. This way you can more easily follow the time progress of an experiment with differing sampling intervals. You do have to feed your graph (and file) both the X and Y data, however.

(BTW, National Instruments is abbreviated NI, not IN  .)

Cameron