USB-231 Taking Measured Voltages and Converting Into Actual High Voltage Values

[tjhanks]

I have already posted this similar question before but I guess I wasn't clear on what I was doing. 

I have a USB-231 MCC DAQ device, and my aim is to measure voltage signals from a high voltage power supply (which the USB-231 should read as 0-10V signal) and convert them into the actual high voltage values coming from the power supply (which is anywhere from 0-250kV), and return the readings and display this value to the user.

I understand the conversions aren't difficult (it is a linear relationship where x is 25), but I am new to LabVIEW and MCC DAQ and am having trouble writing the code and figuring out which display method for the user would be best. I also have to do the same process but converting the voltage signals to pressure and current (1-200 A/Torr). But I'm mostly concerned about the voltage conversions. 

Any help is greatly appreciated and any confusions I am happy to clarify. 

[santo_13]

The simplest answer - multiply by the conversion factor.

If your voltage signal is 1.5V/Torr, then divide your DAQ measurements by 1.5 to convert the voltage into Torr.

Similarly, if your high voltage supply is giving out a 0-10V signal for a 0-250kV output, just multiply the DAQ measurements by 25e3.

If this does not solve your question, please add more information on the part you need help with.

[tjhanks]

I don't know if I am going in the write direction with what I wrote in LabVIEW. I started with an analog voltage input with minimum and maximum values set at 0V and 10V, then displayed it as a waveform graph and saved it to a file, and then tried to scale the data linearly, and then essentially gave up. Not sure if you can tell but I'm very new to LabVIEW lol

[rolfk]

Hmmm, you say you are using an MCC DAQ device but are using the NI DAQmx driver VIs. Despite that MCC is in fact a subsidiary of NI, last time I checked their hardware had different drivers although the latest MCC DAQ LabVIEW driver uses a lot of NI DAQmx ideas to create a similar application interface. The actual implementation underneath is however very different, as the MCC DAQ ULx driver uses a .Net component to interface to the low level MCC UL driver.

[tjhanks]

The USB-231 manual says it supports ULx for NI LabVIEW which is what I've been using. I wouldn't know what drivers I should be using otherwise. 

[GerdW]

Hi tjhanks,

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@tjhanks wrote:

The USB-231 manual says it supports ULx for NI LabVIEW which is what I've been using. I wouldn't know what drivers I should be using otherwise. 

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Your image clearly shows DAQmx functions, so you are NOT using ULx functions…

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@tjhanks wrote:

I have already posted this similar question before but I guess I wasn't clear on what I was doing.

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When you reference older messages you should provide a link to them!

You already got an answer more than 2 weeks ago: what's wrong with that answer?

[tjhanks]

This is what is listed for the device on the MCC DAQ website, I downloaded using the link from www.mccdaq.com.

Again, I don't know what other drivers I would need. 

I understand how to do mathematical conversions, what I am confused by is how translate the input of voltage and scaling/converting that to the voltage I need in LabVIEW. 

[rolfk]

You posted first about wanting to try to use the MCC USB--231 and then in your next post added an image called adc voltage conversion code.JPG. This pic clearly shows DAQmx VIs, which is what we have been wondering about.

It's not enough to simply install the MCC DAQ ULx driver, you also need to use its VIs instead of the DAQmx VIs.

As to scaling, you get voltage as the USB-231 measures it and want something else. Calculate the scaling factor and optionally the offset you need and simply use a n add operator for the offset and a multiplication operator for the scale to "change" the returned value from Volt into whatever your sensor measures. That's it! There is no other magic necessary.

[tjhanks]

Okay, that was helpful. Again I'm very new so a lot goes over my head. How is it that I downloaded ULx for NI LabVIEW but can't find the VI's? 

Thank you for all the input it is very much appreciated. 

[santo_13]

As per the ULx user guide, it should be available under User Libraries»ULx for NI LabVIEW

The ULx APIs are similar to DAQmx but has a blue banner at the top with the text ULx