Obtaining zero values to use for data calculation

[glskinner]

Hey guys, I'm looking to "capture" a zero reading before I start my data measurement. I have 4 analog channels that are running continuously through a producer/consumer architecture. I want to push the "start" button and hold the most recent value for these 4 channels in order to compute some conditions later on in my code. Is there a way to do this without using local variables?

[GerdW]

Hi glskinner,

usually you use ShiftRegisters to "hold" values. No need for locals...

[glskinner]

Hi Gerd, How do I hold these values if I'm taking continuous data? I want to store them once an event happens.

[GerdW]

Hi glskinner,

the standard pseudo-code would look like this:

IF event THEN
  store new value in shift register
ELSE
  keep old value in shift register
ENDIF

 A simple Select function can help here...

[glskinner]

so, something...(big something) like this?

[GerdW]

Hi glskinner,

no, you did not follow my pseudo code. You always keep the old value in the shift register...

[glskinner]

Old values are coming from the right side of the shift register..correct? And the most recent are on the left?

[GerdW · Accepted solution]

Hi glskinner,

when you're unsure about usage of shift register you should take the online courses available at NI.com!

See this:

[glskinner]

My data is coming from a continuous 1d array. Could I index it into a for loop and use the method you described above? I see that the true selector is a constant/control. I want to read my analog channel (indicator)...and get the most current value passed from the array.

[GerdW]

Hi glskinner,

what is a "continuous array"?

What means "pass a value from an array"?

Yes, you can index values from an array using IndexArray. (Did I mention online training courses before?)

Yes, you can "read your analog channel". What's the problem here?