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Why does the DLP tend to flat line after running 5 or 6 scans?

Vaibhav Gupta6
Prodigy 65 points
Other Parts Discussed in Thread: DLPC350

We are attempting to run some scans on DI water, but we see that we flatline after every 5-6 runs. This leads us to restarting the DLP. 

This is what we mean by flatlining. The same sample was originally providing data 2 runs prior.

 

  • 0
    TI__Guru 54635 points

    Hello Vaibhav,

    Welcome to the DLP section of the TI-E2E community.

    Thank you for letting us know about this behaviour.

    There are several possiblities:

    1. Somehow the "Take reference scan" was accidentally pressed storing the sample spectrum as the reference.  If this happens then the sample would be compared to itself and there would be no absorbance relative to itself.
    2. The connector to the illumination may need attention.  If the connection is not good and the reference was done and then the illumination connection changed so the lamp got brighter then graph may show 0 absorbance.
    3. You are using an older version of the software.  Please let us know which version of the DLPC350 firmware and which version of the Web server page you are running.

    If none of these are applicable, can you tell us the specifics of your methodology?

    Fizix

  • 0 in reply to Fizix
    Prodigy 65 points
    Hi Fizix,

    Thanks so much for a prompt reply.

    1. I don't think we pressed "Take a Reference Scan" We attempted it again and received a similar response after 4-5 sample test.

    2. In case it is a problem with the connection, how would you recommend us go about it? I'm afraid to touch too many of the electronic components in the case I short or break something.

    3. We are using SW 1.0.0 Which I'm guessing is outdated? Do you have any ways to update this from a Mac or Linux, or is a windows required for this?

    As far as our methodology, our reference is set to the cuvettes that were provided to us the the evaluation model (we're particularly concerned with wavelengths less than 2000, so it should be ok). We then run a sample of DI water, followed by which we run around 30 samples of various solutions. We wash the cuvettes with DI water and dry with a hair dryer before switching samples.

    Regards,
    Vaibhav
  • 0 in reply to Vaibhav Gupta6
    TI__Guru 54635 points

    Hello Viabhav,

    The current versions are:

    • V2 for the DLPC350 firmware which can be found on this page:

    http://www.ti.com/tool/dlpr350 - the row that has the download bar showing.  The installation package should have instructions for updating over USB.

    • V2.0 for the Web interface software the MicroSD image for Windows and Linux:

      http://www.ti.com/tool/dlpnirscanevm - scroll down to "Available Versions", download and follow the instructions in the download package.

    I hope this helps.

    Fizix

  • 0 in reply to Fizix
    Prodigy 65 points
    Hi Fizix,

    Thanks for your input. The firmware has been updated, and we no longer getting a flat line or NaNs!

    However, now the values that I have been getting are all extremely negative (and are along the same order of magnitude as well). This happens regardless of the type of scan I run and for the reference so I'm assuming the DLP is working correctly as its fairly consistent. Does this happen due to integer overflow? Sorry for the numerous questions.

    Regards,
    Vaibhav
  • 0 in reply to Vaibhav Gupta6
    TI__Guru 54635 points
    Hello Vaibhav,
    Between this and the other thread you have, you may try reloading the Sitara v2 image from SD card. The symptoms are suggestive of a possible corruption in the Linux load on the Sitara image.
    Fizix