Data Acquisition: Gaps in chart.

[rajiv85]

So I was a bit puzzled to see a gap in my graph.

I made a simple DAQ using DAQ assistant in a while loop to acquire 4 Analog Voltages.

Settings as shown:

And in red it shows a gap.

When I use N+1 sample then the gap is gone.

Clearly taking example of N=10

So if the DAQ starts at time 0 ms, then it acquires 10 samples at time 9ms, so there is a gap between 9 ms and 10 ms.

Now if I connect the data to a chart, there is clearly gaps between the acquired measurements. If I change to continuous mode, then the gaps are gone in my chart.

Now if I add N+1, this means am now taking n+1 measurements.

Am not sure how to deal with this.

Any tips and advice?

[crossrulz]

What exactly is the task you are trying to accomplish?  I am not understanding what your problem is or if you even have one.

[rajiv85]

I have been trying to understand the issue myself.

So this is what I observe with Acquisition mode: N sample, 50 samples, Rate 1000 Hz. Clearly there are gaps in my chart. When I switch to continuous the gaps are gone. Also now I see that the N+1 is not necessary. So are these gaps appearing due to the delay in the loop? There are no timers in that loop: just a simple DAQ assistant in a while loop.

[altenbach]

Your image does not show any gap, just the end of the trace at the sample with index # 49 (0..49 is 50 samples, nothing wrong with that. If you don't want the scale to go the the next round number, set the x-axis to not "loose fit")

You talk about charts. Do you have a graph or a chart and do you know the difference?

Can you attach your VI?

[johntrich1971 · Accepted solution]

If you want a continuous signal then you should acquire continuously.

[rajiv85]

It is a simple DAQ. Yes I know the difference between a chart and graph. The graph will take only measurement from one loop while the chart adds all the measurements as long as the loop is running.

In the end, I just want to confirm that I should be using continuous mode rather than N sample? As am getting continuous gaps in my chart with N sample as shown above.

[rajiv85]

Thanks for the tip about loose fit!