Creating A LabVIEW VI with a USB-6008 DAQ to read Load Cell data

[zmcb25]

Hello,

     First I would like to apologize for asking help with something that is most likely very simple to figure out, but I am incredibly new at this.

     I am trying to create a VI for load cell data acquisition. I am using a USB-6008 with an SM-10 S-Beam load cell (if that matters). I need to obtain data graphically from load cell readings, but rather than having the data recorded continuously, I need to be able to take one data recording at a time. So to put it simply, the VI must not plot the data point until a user triggers it by pressing a button.

Please let me known if more information is needed. Thank you.

[Ray.R]

How far did you get with your project thus far?

Did you create a project?  If not, that would be your first step.

Tell us more about your requirements.  Is this for a school project?  a personal project?  something that you are implementing at work?

The reason for asking is to plan for scalability.  However, it is possible to architecture / design the code in such a way as it will scale.

You first need to familiarize yourself with some of the concepts in LabVIEW.  For a simple project with user interaction, I would propose starting with a producer consumer with events.  When creating a project and then adding your main VI you can select from the menu and you will get a very basic code template.

Start with the ability to trigger an event by clicking on a button (ie: Start).  Take one sample.  Display the data in a numeric indicator.  Is the value correct?  If so, then define how you want to sample your complete set of data.  You will probably want 2 controls:

1. time between each measurement

2. duration of the measurements.

(alternative to 2 or in addition to 2:  stop button to manually stop the measurements).

Start with this and let us know how it goes.  This is a very basic implementation.  To get you started.

[Koolbro360]

I know the project he is referring to I can shed some light on the VI thats needed. The required content is the use of two Numerical controls that allow one to zero and calibrate the load cell output. Then, subtract the zero value from the DAQ Assistant output in the block diagram and multiply the result by your calibration factor. Basically he needs the load cell calibrated and then used to measure a distributed load between two separate load cells.

[Ray.R]

It sounds like a school project 😄

Do you have any progress with your project?

[zmcb25]

Apologies for the late reply, for some reason i wasn't getting notified via email when a response was made on my forum link. Yes, it is a school project.

The good news is that I have figured it out! And I have gotten my VI to work quite well. However, the only issue I am having now is zeroing the analog output from the DAQ assistant (It's physical channel is to a USB-6008). Since load cells are incredibly sensitive devices, and the signal input to the DAQ is in mV, I was hoping for a means to alleviate "noise". I have tried a few sub-VIs that i have found online, but nobody seems to use a USB-6008 for load cells, so they do not work very well. Further, I have also tried means of statistical analysis functions to take the mean of the output, but that also is giving me grief 🤔.

Any thoughts?

[GerdW]

Hi zmbc,

---

@zmcb25 wrote:

Any thoughts?

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When there are problems in your VI you should attach your VI…

(Don't forget to include typical data as default data in your frontpanel elements.)

[Koolbro360]

Develop a LabVIEW vi to record load cell output with a 6008 DAQ device.
Modify your vi to include two front panel Numerical Controls to allow you to zero and calibrate the load
cell output. Subtract the zero value from the DAQ Assistant output in the Block Diagram and multiply
the result by your calibration factor.
Develop the calibration factor by placing a known weight on the beam over A (or B) and reading the load
cell output (previously zero-adjusted to remove the beam weight).

1. Next proceed to place the load at measured positions along the beam and develop the
experimental influence line.

2. Take the beam off the load cell and find the zero load output voltage again. Reset your zero
control. Place a known load on the load cell (without the beam). Reset your calibration control.
Reposition the beam on the load cell. Place a known load in the middle of the beam. Measure
the RA. Does it agree with the theoretical value?

3. Repeat for other beam

I just need general help. I'm not the best at LabVIEW so any assistance would be greatly appreciated. 

[GerdW]

Hi Koolbro,

no need to create a new thread on the very same topic: stick with your thread!

Why did you even use a wrong title to your message when you are still using that USB6008?

(Please discuss this whole problem with your colleague and reply to the questions of me and others in this thread…)

[Koolbro360]

I couldnt adjust the content to say the correct DAQ, but we are using a USB6211

[GerdW]

Hi Koolbro,

the USB6211 doesn't make a huge difference to an USB6008 in terms of DAQmx task defnitions.

So again I have to ask:

What have you tried? Where are you stuck?

Why don't you atach your VI(s)?