Analog signal (voltage) comparator

[zezendapuss]

Hey guys,

I would like to compare an incoming voltage signal with a constant value i.e. compare elememts of incoming analog signal to a contant. if the signal exceeds the reference, i would like to have a digital output to trigger an exernal LED circuit. 

The following method generates an array of boolean, i would like to have a single boolean value based on comparison of element-constant comparison.

I saw an old example, but my same program does not work.

[crossrulz]

Use OR Array Elements

[udka]

-Did you miss step 4 in other image? 

-To split the signal to get Numeric value and do comparision as in other image.

[zezendapuss]

Hey Uday,

No. I think step 4 is unbundling the two waveforms. The blue wire is still a waveform signal compared to a constant. Apparently the example does not show any usage of OR etc.

[udka]

Waveform datatype has three components t0-Timestamp,dt-time difference between samples,Y-1D array of values of samples of that signal.More on wavefrom data type :https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8qkSAC&l=en-US

-Now you want to compare with what?

-When you right click on blue wire(dynamic data type) did try to create indicator? What it shows? What type of indicator does it allow? : https://www.ni.com/docs/en-US/bundle/labview/page/using-the-dynamic-data-type.html

[zezendapuss]

Thanks for your suggestions uday.

Basically i am recording an analog signal and would like to generate a digital output whenever the value of analog signal crosses a certain threshold. Maybe what i am doing is not the right appraoch. Could you please suggest something?

thanks a lot!

[GerdW]

Hi zezendapuss,

use an "OR array" function as suggested before on your boolean array to get a scalar boolean value…

[udka]

As Pointed by others, you are comparing scalar value to array of numbers: So you will have array of boolean giving the comparision of each element in array vs constant value.

-You need to use https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/functions/or-array-elements.html

to get the Boolean value so that if any one of boolean in array is TRUE it will result in TRUE.

[zezendapuss]

Thanks GerdW, will do that.

slight off beat question. how fast can i trigger a digital output based on the results of comparison. is it possible to generate digital output at the rate of 200-300Hz?

[Vincent90]

It depends on the hardware you are working with...