storing data after certain threshold

[shinjita]

hi....iam acquiring data using usb 6008...the thing is i dont hv to store all the acquired data...but i hv to start the storing only when it reaches a certain voltage...can ne one tell me how to do it

Shinjita

[lmtis]

Do you only need to store data above the threshold, or record all data once the threshold is crossed?

[shinjita]

start recording after the particular threshold

[aeastet]

A state machine with producer consumer arcetecture would be how I would begin. Look at the examples to see how each system operates and come back for help.

[lmtis]

I'm not clear which part of the task you are having trouble with.  If it is the data acquisition part, have you looked at the examples that ship with LV?

[shinjita]

can any one suggest how to build a comparator usin labview...i mean from where can i get an opamp

[Dennis_Knutson]

Op amps are electriconic devices. In LabVIEW, the comparison functions are on the (surprise!) Comparison palette. Look and you will find such things as Greater Than, Less Than, Equal, etc.

I would recomend the basic LabVIEW tutorials.

[tbob]

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@shinjita wrote:

hi....iam acquiring data using usb 6008...the thing is i dont hv to store all the acquired data...but i hv to start the storing only when it reaches a certain voltage...can ne one tell me how to do it

Shinjita

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Please don't use texting shortcuts here.  Spell out the words.  It doesn't take much effort to type have instead of hv, and any instead of ne.  Shorthand is hard to read and slows down the process of reading and replying.

For your problem, use a While loop to capture the data.  Wire the output of your comparison to a case structure.  Put code to store the data in the appropriate case (True or False).  Put a small delay, Wait(ms), in the loop to avoid chewing up 100% CPU time.

[shinjita]

yes i know there are greater than and less than functions but they return the value in boolean whereas i need it in voltage or the input that iam giving

[shinjita]

i need to have the input value since i need to do further analysis on it