Why is my x y graph not showing any graph?

[Monkspade]

Hi,

I am making an hartmonitor VI for school. I managed to calculate the hartbeat. I connected it with a cluster bundle to my x y graph. But my x y graph doens't show anything. Please can you tell me why. This is my VI  

[bfarley · Accepted solution]

At one point, you are dividing an array by an empty array constant.  The output of that operation is always an array with 0 elements

Bill F

[Monkspade]

Ok thanks,

I understand now. But is the way I calculated the heart rate going to work for real time measurement with a DAQ-card and LED sensor.

Abi. This is the corrected VI:

[Coq_Rouge]

Please go to the toolbar then select help->find examples. Search for peak and then open the "Peak Detection and Display.vi". Let us continue the discussion with this VI as a template. Your VI will never work as it is now.  

[Monkspade]

Coq rouge ,

I am now using the other peak detector. The heartbeat is now lower. But I don't really know if it i will work now in realtime.

Abi

[Coq_Rouge]

No it will not work. You are doing things the wrong way. You must use the peak locations. The first beat is peak(1) minus peak(0), the nest beat is (2)-(1) and so on. If you divide with the sample rate you will get the time between heart beats. This is equal to the period time. The frequency is the reciprocal(1/x). You can go directly to frequency by dividing sample rate with beat interval in samples. Which sample rate do plan to use and how often will you update your result in real time?

[Monkspade]

 Coq  rouge,

I think my acquisition mode will be continuous sample with a sample rate of 1000 Hz  and sample period of 0.001 s.

[Coq_Rouge]

1000 Hz sound good. I guess you could have gone lower but stick with 1000 Hz. It should be more than enough to update your beat data very second 

[Monkspade]

Coq rouge,

I don't understand what you mean, because I am using the peak locations and with de derivative I am calculating the number of samples between peaks. And I also divided it with de sample rate in de VI I showed you before. Can you please show me an example?

Abi

[Coq_Rouge]

You DO NOT need the derivate consentrste on the locations array. As told I  you.

The first heart beat is the value in locations[1] minus the value in locations[0]. A for loop running #found-1 should do the trick