Triggering a snapshot of data while simultaneously logging all data (from same DAQ)

[ntsirak1]

Hello,

I am trying to log all data from my DAQ at a slow frequency, but I want it to capture at a higher frequency when a certain trigger occurs. As of right now, I have two separate while loops going at once (one with the slow logging and the other with the trigger logging). Is there a better way to do this? Is it possible to reduce this down to one while loop and still capture all the data in real-time? I found something in the DAQ assistant called "Logging" but I am not sure if this will help in this case. Thanks!

*Note that the "Enable Snapshot" and "Take Snapshot" buttons must be toggled from ON to OFF consecutively, as of now. I.e. Enable ON, Enable OFF, Take ON, Take OFF

[ntsirak1]

Anyone?

[kruiz17]

Hi ntsirak1,

I have a couple suggestions for you. First is to let you know that you can acquire at a certain frequency and then decimate the acquired data to log certain samples, giving the impression that you are logging data at a slower rate. Here are some LabVIEW functions you could use to decimate the acquired data: 

https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/functions/decimate-1d-array.html

https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/vi-lib/analysis/2dsp-llb/decimate-continuo...

Additionally, you can use the DAQmx Configure Logging VI to save your acquired data to a TDMS file, but once the acquisition has started you cannot stop the data logging process. Here’s some information on the DAQmx Configure Logging VI:

https://www.ni.com/docs/en-US/bundle/ni-daqmx-labview-api-ref/page/vi-lib/daqmx/configure/task-llb/d...

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000kGedSAE&l=en-US

Lastly, here’s an example that I’d like you to take a look at. This example implements a continuous acquisition with producer/consumer architecture that allows you to enable/disable data logging with a Boolean button. I think this example might come in handy for your application.

https://forums.ni.com/t5/Archive-TKB/Using-Producer-Consumer-Architecture-for-DAQmx-Read-and-Write-t...

I hope this information is useful to you. Let me know if you have any more questions or concerns.

Regards

[ntsirak1]

Thank you for your response! This might be exactly what I'm looking for