• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 48 subscribers
  • Views 759 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMP91050 Differential Measurements

William Spencer
Prodigy 40 points
Other Parts Discussed in Thread: LMP91050SDEVAL, LMP91050, LMP91051

I want to make a differential measurement based on two NDIR sensors.  I think this is a fairly common practise with NDIR sensors and suspect somebody has already worked this out.   At the moment, I have two NDIR sensors, each is connected to its own LMP91050SDEVAL board that is connected to SPIO4 boards  which plug into separate USB ports.  Both sensors are working separately but I can not figure out how to make the Sensor-AFE-for-91050 software collect when both sensors are connected to USB ports.  Apparently the software is only seeing one board, the first USB port it finds.  Is there some way to configure the software to set the USB ports so I can collect signals from both sensors?  The computer could easily run two copies of the software but I do not see how to set the USB port that is being used for a given copy of the software.  In the Device Hardware view I can see both of the NSC_USB boards.  Both are assigned to location 0 but have different board ID numbers.  There are no error symbols on either USB port. 

Another confirguration that we will eventually want to test uses 4 or 5 different sensors.  Ideally these would have only one USB port but independent LMP91050s.  I wonder if there is a way to link multiple LMP91050SDEVAL boards to a single SPIO4?  Do I need to purchase a software development kit to communicate to modules?

 

  • 0
    TI__Prodigy 420 points

    Hi William,

    I'm replying to the first part of your question -

    Q) Is it possible to capture data from multiple SPIO4 boards?

    A) The Sensor AFE software has been typically designed to work with one board only. The software will recognize the first USB it sees and once it recognizes it, its all ready to capture data. Even multiple instances of the software might not work because both instances might end up recognizing the same USB. I would say, the best way to achieve this is to either use multiple computers or using a virtual machine on the same computer. 

    Hope this helps. You'll receive answers to your other queries from the applications engineer for LMP91050.

    Regards,

    Shrikrishna,

    Texas Instruments.

  • 0 in reply to Shrikrishna Srinivasan
    Prodigy 40 points

    Thanks for answering.  I was hoping it could be done.  Interestingly the driver knows there are two boards connected and tells me this on boot of the applications but you are right the application seems to just work with only the one board.  I suspect that we only need to tweak the software code.  Is there a way to get access to it?

     

  • 0 in reply to William Spencer
    TI__Intellectual 2630 points

    William,

    The DLLs we used can only support one SPIO4 board so providing you the software code will not help you. We plan to release a two channel version of the LMP91050 device which will be called LMP91051 which will have it's own board and software and allow you make your differential measurement based on two NDIR sensors. We plan to release early October. Please work with your local sales rep for samples in advance of this date.

  • 0
    Prodigy 10 points

    A have two channel thermopile HTS E21  http://www.heimannsensor.com/Datasheet-3a-Dual_Quad_rev2.pdf . Can be used "IN" and "CMOUT" pins of  LMP91050 as differential input?  I plan to connect the pin No2 of thermopile to the pin "IN" and pin No.3 to the pin "CMOUT" correspondingly. Pin No.4 of the thermopile is connected to the ground.  Can I get differential signal between thermopile 1 and thermopile 2 in a such manner?