Updating waveform graph each second

[Amr95]

I am acquiring data using daqmx function in a while loop and I want to display the real time data on a waveform graph. I need the graph to update each second with the new data acquired and ignore the data of the last second/seconds. I created a simple program to show what I am doing, the problem with my current implementation is that the new data keeps getting appended to the array and the waveform graph ends up acting as a waveform chart and shows the whole array instead of the data of the last second. I would be grateful if someone instructs me to how to implement it right 🙂

[GerdW · Accepted solution]

Hi Amr,

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@Amr95 wrote:
I created a simple program to show what I am doing, the problem with my current implementation is that the new data keeps getting appended to the array and the waveform graph ends up acting as a waveform chart and shows the whole array instead of the data of the last second. I would be grateful if someone instructs me to how to implement it right 🙂

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• As your loop is set to iterate 1000 times per second you should update your graph only each 1000th iteration! Using Q&R on the loop iterator will easily determine that…
• As your loop is collecting ALL samples in this array you should only take the last 1000 samples to show them on your graph - as you want to present the samples of the last 1 second! (Build arrays this way is considered highly inefficient…)
• When using real DAQmx functions you could set a samplerate and read the same amount of samples to effectively get new data once per second…

[melisakocak]

Can you demonstrate your solution GerdW, I would also like to see the solution for this problem.