how to measure the inductance with a ELVS board

[jingrui]

Hi,
 
I am a graduate student and working on a project. In this project, I need to measure the instantaneous inductance which keeps changing. And I only have a ELVS board and LabView 7.1 in my lab. So does anyone know how to use them to measure the inductance? I really appreciate your help.
 
Thanks
 
Jingrui

[Hani R]

Hi Jingrui,

What version of NI-DAQmx and
NI-ELVIS do you have installed?  If the NI-DAQmx
and NI-ELVIS drivers are installed correctly, you will have a Digital
Multimeter VI found in the LabVIEW functions palette under Instrument I/O » Instrument
Drivers » NI ELVIS » Digital Multimeter.   When you place this VI on the block diagram,
a configuration window will open up.  You
can then select the Measurement Function to be inductance.  Connect one wire to the CURRENT HI pin and
one to the CURRENT LO pin on the NI ELVIS for an inductance measurement. 

[Hani R]

Hi Jingrui,

The NI-ELVIS Digital Multimeter VI has a Measurement output which you can connect to other VIs.  I?m not really clear on what you mean by wanting
to use the inductance value as an input signal. 
What exactly would you like to do with the inductance value (store/output/process)?   Post back with some more details about your application so we can assist you further. 

If you are looking for more general information, there are some great
resources available on how to program in LabVIEW.&nbsp; Check out the&nbsp;<a href="http://zone.ni.com/devzone/cda/tut/p/id/5243" target="_blank"></a><a href="http://zone.ni.com/devzone/cda/tut/p/id/5241" target="_blank">LabVIEW Introduction Course - Six Hours</a> and the <a href="http://zone.ni.com/devzone/cda/tut/p/id/3116" target="_blank">Complete Data Acquistion Tutorial</a>. &nbsp;&nbsp;&nbsp;

[jingrui]

Hi, Hani
Thanks for your patience. I am a beginner who just start to learn how to use LabView, so your guidence is critically helpful to me. Let me&nbsp;explain my project to you briefly so that you can get a idea about what I am trying to do.&nbsp;&nbsp;
&nbsp;I wanna measure the inductance of a magnetic system, whose inductance keeps changing as I change the reluctance of it.&nbsp; I am trying to use the DMM to measure the instananeous inductance of this system, meanwhile I want to build a VI program to process the instananeous inductance&nbsp;value. There is a fixed relationship between the inductance and the reluctance, so I want to know the relucatnce by processing the inductance value at a certain time.&nbsp;
Can you get a clear idea about what I am doing? I hope you can give me more help on this,. &nbsp;I will go over the resource you gave me in last reply and&nbsp; try to make some progress on how to program in labview.
Thanks again!
Jingrui

[Hani R]

Hi Jingrui,After placing the ELVIS Digital Multimeter VI on the block diagram, selecting inductance in the configuration window, then pressing ok on the configuration window, you should notice that the Digital Multimeter VI will reconfigure its inputs and outputs.&nbsp; The Measurement Output (as with other outputs) will be found on the right side of the VI.&nbsp; You can scroll over to this terminal and wire the output to a Formula Node or a Formula VI.&nbsp; To create the inputs and outputs on the Formula Node, right click the
Formula Node and select Add Input or Add Output.&nbsp; You can then name the
inputs and outputs as I have done.&nbsp; Type in your formula in the Formula
Node but make sure you use correct syntax.&nbsp; In the image below, I wired the Measurement Output to a Formula Node.&nbsp; <img src="http://forums.ni.com/attachments/ni/220/400/1/Elvis%20DMM.JPG"> Notice that the inputs and output of the Formula Node are labelled.&nbsp; If you need help using the VIs, the LabVIEW help is a great place to read about the details of their functionality.&nbsp;&nbsp; Message Edited by Hani R on 12-01-2007 12:29 PM

Elvis DMM.JPG:
http://forums.ni.com/attachments/ni/220/400/1/Elvis DMM.JPG

[jingrui]

Hi, Hani
&nbsp;
I can not find the ELVIS Digital Multimeter VI as shown in your reply in the labview functions, so can you tell me where to find it? I find some VIs in the instr driver menu but they don't look like the one in your reply.
&nbsp;
Thanks a lot!
&nbsp;
Jingrui

[Hani R]

Hi Jingrui,

The following KnowledgeBase article describes the error you are getting: <a href="http://digital.ni.com/public.nsf/allkb/351C593EA51984D686256F65006007B5?OpenDocument" target="_blank">KB
3G8AEEBJ: Why do I get Error 9320 When Running a VI With NI ELVIS</a>.&nbsp; It
sounds like you have selected the incorrect device.&nbsp; To use NI ELVIS you
need to have it connected to a DAQ card installed in your computer.&nbsp;

When the DAQ drivers were installed, a program called Measurement and
Automation Explorer (also known as MAX) should have installed with it.&nbsp;
When you open the program, expand the Devices and Interfaces tab.&nbsp; If you
have a DAQ card, you will find it under NI-DAQmx Devices with the device number
listed next to the device.&nbsp; Perform a search on National Instruments' <a href="http://www.ni.com/" target="_blank">website</a> if you are not sure what the type of
hardware the product name corresponds to.

[jingrui]

Hi Hani
Sorry to respond you two days late. And I've got my program work now. I just used the example VI, Basic DMM VI,&nbsp;given by the ELVIS and modified it to what I want as you told me, and fortunately I figured out the reason&nbsp;why it gave me the error warning.&nbsp;&nbsp; With the program I am done with my project.
I'd like to post my block diagram here, but I can not post it here by using the 'insert a image' command of this forum.
And I would like to show my gratitude to you here, without your help, I would never stand a change of getting it done, I really appreciate it! Since I am studying how to program in Labview now, I am sure I will have a lot questions to ask you in the near future. ^_^
Thanks again and ll the best to you!
Jingrui