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20 channel chatter monitor - X series NI 6343

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Hi All, I'm new to the forum and just getting my feet wet in developing VIs. I find that I need to make a VI that can act as a Chatter monitor. I need to set a low threshold voltage, and monitor 20 voltages simultaneously, detecting if any of them go below the threshold for longer than one micro second. If there are any events longer than one microsecond, I want to log the channel number on which it occurs, the timestamp, and then continue on monitoring. I have an X series NI 6343 to work with.

 

My question is, is something like this possible with a NI 6343?  So far I have perused through the NI 6343 documentation  (X Series Data Acquisition: 500 kS/s, 32 AI, 48 DIO, 4 AO).

 

Purely by looking at sample rate (500 kS/s) that seems like it's too slow to poll for a microsecond event, but then the documentation lists (timing resolution: 10 ns) which seems promising. What is the difference between sample rate and timing resolution in this context?

 

Appreciate any help!

 

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Message 1 of 6
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Hi L2,

 

Purely by looking at sample rate (500 kS/s) that seems like it's too slow to poll for a microsecond event,

Yes, that's true. With 500kS/s you will get a sample each 2µs.

 

but then the documentation lists (timing resolution: 10 ns) which seems promising. What is the difference between sample rate and timing resolution in this context?

Simplified: Timing resolution will determine the accuracy of the sample clock. At 500kS/s you will read a sample each 2µs with an accuracy of ±10ns…

Best regards,
GerdW
CLAD expired, using 2009SP1 + LV2011SP1 + LV2017 (+LV2018 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

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Thanks for your response!

 

I have another question/idea. Let's say we can nix the idea of polling contantly to check for 1µs gaps in the voltage.  I have been reading about triggering and finding digital or analog edges. Is it possible to trigger an event when the voltage drops below a threshold, record a timestamp, then trigger another event  when the voltage rises above a threshold, and record a timestamp. Basically, I'm asking does the 500ks/s apply with this method, or can we take advantage of the 10ns resolution.

 

I apologize for not having any code to upload, I am trying to first see if this is feasible with my hardware before spending the time, because I may need to rent equipment if this is not feasible.

 

thank you!

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Message 3 of 6
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Hi L2,

 

trigger an event when the voltage drops below a threshold, record a timestamp, then trigger another event  when the voltage rises above a threshold, and record a timestamp.

To detect voltage levels you need to sample the voltage signal.

And for sampling the voltage signal the 500kS/s sample rate applies…

Best regards,
GerdW
CLAD expired, using 2009SP1 + LV2011SP1 + LV2017 (+LV2018 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

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Is there any NI hardware , or even a toolkit that could interface with non-NI hardware that supports this kind of timing requirement? Surely this can't be the first application that needs it. I think my problem is just that if there is a specific way to implement something to detect a 1µs gap in voltage, I just don't know what it would be called, and therefore can't research it.

 

My alternative is to rent chatter monitors that are dedicated to this. But in this industry it would be helpful if I can do it in Labview so that I can record multiple events / customize how many channels to use etc.

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Hi L2,

 

surely NI also sells hardware capable of higher sample rates…

Best regards,
GerdW
CLAD expired, using 2009SP1 + LV2011SP1 + LV2017 (+LV2018 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

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