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Microphone Voltage RMS

Hi!

What module is it that you are using inside your cDAQ chassis? The model number 9174 is the model number of the chassis, but there should be a model number like "9211" on the module you are wiring into.

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Message 11 of 15
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Hi,
Yes it is the 9223

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Message 12 of 15
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Unfortunately, your device does not have that capability to measure RMS Voltage. I believe that functionality is only built into the NI Elvis board, which is one of National Instruments' Educational Products. 

To find the RMS Voltage, you will need to process it in software. LabVIEW has multiple functions that can calculate RMS Voltage. To determine the vi that will best suite your needs, you can look at the help files below. They will give explanation of how the calculation is done. 

RMS vi: http://zone.ni.com/reference/en-XX/help/371361H-01/gmath/rms/ 
RMS PtbyPt VI: http://zone.ni.com/reference/en-XX/help/371361H-01/ptbypt/rms_ptbypt/ 
Cycle Average and RMS VI: http://zone.ni.com/reference/en-XX/help/371361H-01/lvwave/cycle_average_and_rms/ 
Statistics Express VI: http://zone.ni.com/reference/en-XX/help/371361J-01/lvexpress/statistics/ 

Message 13 of 15
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Thank you, 
This has helped a lot. 
I have a final query which is:
I am trying to set up a trigger for my device, for which I am able to use the Trigger and Gate express VI, but I wish to make my program without express VIs.
So I am using the DAQmx Start Trigger. I am trying to use the device that I am taking the signal from and when this goes above a certain value it will begin recording data. Attached is the start of my attempt, but when I look for my device I am unable to find it in the sources. Is there a way around this?

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Message 14 of 15
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I'm not sure that method's going to work very well, it's best used for when you have a seperate clock device or channel which you can get a digital edge from and then use that as a que to start your main acquisition.

 

You probably want to try out this :

http://zone.ni.com/devzone/cda/epd/p/id/151

Or instead perhaps consider implimenting the code example attached to this post to a continually sampling system.

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