How to reduce Execution Time

[Khan83]

Hi,

I am using niHSDIO Initiate.vi and niHSDIO Fetch Waveform.vi for data acquisition usin PXI 6541. These functions are used in a sub VI. This sub VI is time critical and it takes approximately 4 to 10 ms. But Ideally it should take 0 ms. How to reduce this time to less than 0.5 ms?

Khan

[altenbach]

What is taking the most time? How big are the waveforms? How are you measuring the time? What do you mean by "time critical"? (Generic term or actual priority setting?

... So many questions, so few details!

[Yamaeda]

I assume you're using some loop for data gathering. If so, initiate should be done outside the loop. Also, getting a very low loop time might be hard, it's usually better to grab a slightly bigger data set and work on that, e.g. grab 20ms worth of data at a time and analyze.

/Y

[Khan83]

Most time is taken by niHSDIO Fetch Waveform.vi, Waveforms contains 512 bits. I measure time using Time Template (data dep).vi, These are used within a while loop. It is of actual priority as data is acquired.

[altenbach]

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@Khan83 wrote:

It is of actual priority as data is acquired.

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I don't understand what this statement means.

[Yamaeda]

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@Khan83 wrote:

Most time is taken by niHSDIO Fetch Waveform.vi, Waveforms contains 512 bits. I measure time using Time Template (data dep).vi, These are used within a while loop. It is of actual priority as data is acquired.

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Yes? Can't you measure/calculate time from a 20ms chunk? If you need the system to stop/react fast to a specific value it shouldn't be in software, but wired back as a trigger.

/Y

[crossrulz]

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@Khan83 wrote:

Most time is taken by niHSDIO Fetch Waveform.vi, Waveforms contains 512 bits. I measure time using Time Template (data dep).vi, These are used within a while loop. It is of actual priority as data is acquired.

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How fast is the waveform being sampled?  You have to allow time for the samples to be gathered in the HSDIO.  So if you are sampling at 50kHz, it takes ~10ms to gather 512 samples.

[Khan83]

Actually my DUT sends Interrupt at 1Khz, this interrupt is used for triggering. I have attached the VIs. I am using PXI 6541for data acquisition and use LabView 2009. If I use Initiate.VI out of Loop as mentioned by Yamaeda, I do not get output.

Khan