Sine Wave Signal @60Hz measurement with NI9205

[MAXD]

Dear All,

I am working with current and voltage signals across 80 channels. The chips providing these signals output a 60 Hz sine wave at 2.5 VDC, rather than the typical 0-5 VDC or 0-10 VDC range. I’m seeking guidance on how to accurately measure this signal or if it's even feasible with this setup. Additionally, could someone advise on the best approach to convert this signal into an RMS voltage?

For context, I am currently using the 2024 LV Base version.

Thank you in advance for your assistance.

[santo_13]

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@MAXD wrote:

Dear All,

I am working with current and voltage signals across 80 channels. The chips providing these signals output a 60 Hz sine wave at 2.5 VDC, rather than the typical 0-5 VDC or 0-10 VDC range. I’m seeking guidance on how to accurately measure this signal or if it's even feasible with this setup. Additionally, could someone advise on the best approach to convert this signal into an RMS voltage?

For context, I am currently using the 2024 LV Base version.

Thank you in advance for your assistance.

---

You can capture this signal using an Analog input card at 120 Hz (Nyquist) or higher, the higher rate the better and do all calculations in the software. The next question becomes the range of voltages to determine the accuracy.

[Bob_Schor]

The NI9250 has a +/- 5 V setting, so you are using 1/4 of this range, making the A/D converter effectively 14-bit, which is better than 1 part in 10,000 (if the math-in-my-head is right).  That should be sufficient precision.

Bob Schor

[MAXD]

So I have close to 114 channels. 
120hz 1sample 

 Then, I have 60 sample and my loop in set to update every second. But it’s too slow. 

[Bob_Schor]

Pictures are useless (particularly when they cross scan lines and are rendered unreadable.  The 9205 only has 32 Single-ended Analog inputs, and if the A/D is set up correctly, should easily be able to handle sampling in the kHz range, so 120 Hz should be trivial.  If you need to run 4 9205s simultaneously (to handle 128 channels), this should add a few microseconds to the code.

If your code can't do that, either there's something serious I've missed about the Hardware (I've never used these modules, am only going by their Specifications) or you code is hopelessly bad.  Write a small Demo Project that tries to take a few samples, preferably in LabVIEW 2021 or earlier.  If you don't have such a version, write it in LabVIEW 202x (32-bit, please) and "Save for Previous Version" to 2021 or 2019, and we'll look at it.

Bob Schor

[santo_13]

If you're focussing only on data acquisition and logging, try out the FlexLogger lite, it does all these without any code.

https://www.ni.com/en/shop/data-acquisition-and-control/flexlogger/select-edition.html