CN0301: Universal LVDT Signal Conditioning Circuit

If you have questions about CN0301, please post them below.

Parents
  • Hi, Brandon,

    I have two questions about CN0301_Evaluation_Software.

    Question 1

    When I choose the units of Inches or Millimeters, the change in value on channel 2 is the same. Why? The units we choose are different, but the change in value is the same. For example, they all go from 0.0156 to 0.0176.

    Question 2

    When I change the maximum stroke range of the LVDT, the values on channel 2 are quite different. For example, when I set 0.20 inches, the value on channel 2 go from 0.0030 to 0.0036. When I set 1.00 inches, the value on channel 2 go from 0.0156 to 0.0176. What the relationship?When you do an experiment, how do you set the maximum stroke range of the LVDT?

    Regards,

    Gissoes

    •  Analog Employees 
    on Jan 7, 2019 3:04 AM over 1 year ago in reply to Gissoes

    Hi Gissoes,

    We have checked and validated the results you were getting for both questions that wrote.

    for question 1: as per reviewing the source code, the conversion unit was not implemented and therefore needs to be added by editing the software where the link was provided by Brandon. 

    for question 2: we were able to encounter same issue when the LVDT sensor was not properly connected to the terminal.  once the connection was fixed properly, the reading correctly corresponds again to the max stroke provided.  kindly make sure that the sensor was properly connected to theboards terminal input connector.

    Cheers,

    Erbe

Reply
    •  Analog Employees 
    on Jan 7, 2019 3:04 AM over 1 year ago in reply to Gissoes

    Hi Gissoes,

    We have checked and validated the results you were getting for both questions that wrote.

    for question 1: as per reviewing the source code, the conversion unit was not implemented and therefore needs to be added by editing the software where the link was provided by Brandon. 

    for question 2: we were able to encounter same issue when the LVDT sensor was not properly connected to the terminal.  once the connection was fixed properly, the reading correctly corresponds again to the max stroke provided.  kindly make sure that the sensor was properly connected to theboards terminal input connector.

    Cheers,

    Erbe

Children
  • Hi erbe,

    You said "once the connection was fixed properly, the reading correctly corresponds again to the max stroke provided",how can I understand it? Can I understand that if the connection is fixed properly, whatever I set the maximum stroke range of the LVDT, the change in value on channel 2 is the same. If not, can you give me an example so that I can judge  whether my connection is right or not. 

    Cheers

    Gissoes

    •  Analog Employees 
    on Jan 8, 2019 3:52 PM over 1 year ago in reply to Gissoes

    Hi Erbe,

    Would you be able to supply a picture of the LVDT connected both correctly and incorrectly, along with the corresponding screen shot of the software.  This would probably help Gissoes figure out what was wrong.

    Cheers,

    Brandon

    •  Analog Employees 
    on Jan 9, 2019 5:54 AM over 1 year ago in reply to Gissoes

    Hi Gissoes,

    I have made some edits with the script and the updated software can be downloaded from this link:

    ftp://ftp.analog.com/pub/cftl/CN0301/1.0.2/.

    let me know if the unit conversion works fine from your end.

    Cheers,

    Erbe

  • Hi erbe,

    Sorry,I was busy with something else the day before, and I didn't reply to you until today.

    I have made some experience with the updated software. There is no problem switching between inches and millimeters. For example, when I choose the units of Inches, the value on channel 2 is -0.0565, and when I choose the units of Millimeters, the value on channel 2 is -1.4335. There is no problem.

    But,when I change the maximum stroke range of the LVDT from 0.20 inches to 1.00 inches, the value on channel 2 also change from -0.0565 to -0.2825. They both have a five-fold change in relationship. Is this right?

    I have anthor question. When I connect LVDT and do nothing, the waveform is shown as follows.

    You can see that the error is quite large. Where do you think this error comes from?

    I did not use the E-100 ECONOMY SERIES LVDT. I used the sensor of my own and have tested the input and output signals of the sensor. There is no problem.

    •  Analog Employees 
    on Jan 14, 2019 1:11 PM over 1 year ago in reply to Gissoes

    Hi Gissoes,

    thanks for confirming that no further issue found for the conversion function of length displacement. 

    the initial value under the max stroke relates to the specs of the included E-100 LVDT for this reference design and its specs can be read from this link:

    https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FE-Series%7FA%7Fpdf%7FEnglish%7FENG_DS_E-Series_A.pdf%7FCAT-LVDT0025

    as what you mentioned above, you were using a different LVDT.  you, therefore,  need to change some of the resistor component values in the reference design that contributes in setting the right scale measurement of its displacement being displayed in the GUI.  kindly refer to page 6 from the datasheet of AD698(https://www.analog.com/media/en/technical-documentation/data-sheets/ad698.pdf) for your reference.   

    and for the error that you are seeing from its acquired data when the LVDT is at its static state which gives you a .00005in as its noise is still in its acceptable range of noise value. 

    Cheers,

    Erbe