Working with shift registers for finding index of threshold point.

[anupam2016]

Hello,

I am trying to find the index of two succesive values using shift registers in a while loop. The index refers to the output of the "threshold pt-by-pt VI".

But, I find that all the shift registers giving the same value.I am visualizing the values using indicators.

In future, I wish to do some arthemetic with the to succesive values of the index.

I am attaching my VI.

Can someone please find what may be the mistake I am commiting.

Thank you very much

Anupam.

[altenbach]

You are looking at three values (op-1, op-2, op-3), not two. What's the purpose of op-3?

Shouldn't you only update the shift register value if the output "detected" is true or "index" actually changes?

[anupam2016]

I think reading op-3 is just for checking, what the index is.

Yes, I think You are right, I need to update the shift register , only when the threshold VI gives TRUE.

Should I use a Case structure to check when to update the VI for this.

Thanks

[crossrulz]

A case structure or a Select function should work.

[anupam2016]

I dont think I need a case structure or a select function. This is because the pt-by-pt threshold which I am using throws the index when the peak is detected (i.e:above threshold).

My problem is storing the 'ith' and (i-1)th index temporarily so that I can do some arthemetic and get the required. I  was trying to do this using shift registers but unfortunately it did not work.

Thanks.

Any help will be of use to me.

[anupam2016]

My update VI.

With the Case Structure, Both of them the previous and the final still show same values.

Thanks.

[crossrulz]

Your problem is that you are resetting your index when no threshold was found.  Use the value currently in the shift register instead.

[anupam2016]

Thanks.

I constructed the VI and ran the program, the results were not as expected.

I was getting the value of heartbeat which should remain constant decreasing with every iteration.

Any hints to this problem.

P.S:Is the new logic implementation causing problems.

[crossrulz]

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@anupam2016 wrote:

I was getting the value of heartbeat which should remain constant decreasing with every iteration.

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Yeah, that makes sense.  You should probably only calculate the heart rate when a threshold is detected (hint: use a case structure, and you should probably remove the Select and just put that logic in the case structure).

[anupam2016]

Hi,

I am posting the modified VI with the logic inside the case structure.

The results are for the values below the threshold the heartbeat gives non-zero values but decreasing.

For values above the threshold the heartbeat is infinite, meaning the the difference is zero.

Any clues?

Thank you

Anupam