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Hysteresis measurement with metal plate

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Hi, all. I have task to figure out. I want to measure Hysteresis of elastic coupling. For measure torque I have two strain gages on 90 degrees (NI 9237 Half Bridge II). After little calculation I now the torque. In another hand i mesure rotation angle of motor with metal plate with 52 tooth (gear). For rotation angle i use NI 9401 digital input. To bild hysteresis i have to now on every couted tooth the torque. I tryed example Multi-Function-Ctr Retrigg Pulse Train Generation for AI Sample Clock but always graf give me straight line. Can anyone help me with that? Is there more better example for me, or clips in internet to show me how to do it? Thanks previously.

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Dear stefo83,

from what I understood, you want to measure the value on NI 9237 on every digital event coming from the NI 9401 (rotation of the metal plate). In this case I am not sure what do you need the counter for.

Do you want to acquire 100 samples of the signal every time you get a digital event?

Does the program give you proper values if you are not using the counter as sample clock source?

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Hi, MateuszStoklosa. Thank you for reply.

Yes, I don't need counter, but I need for example 1000 samples from first digital edge to second. ( on metal plate). I try start trigger. In slow speed (turn around with hand) of metal plate everything is OK. But if I turn around metal plate fast the trigger slowing down. For one cycle on metal plate on slow speed cout me 52 digital edges 1000 sampels for edge (metal plate is with 52 tooths), but on fast speed count me 16 edges. Is that problem coming from syncronise of digital input and analog input?

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Accepted by topic author stefo83

It this case the problem might be, that either the DAQ card cannot rearm the triger fast enough, or the acquisition takes too much time.

In the configuration from the screenshot I can see you want to acquire 100 samples at 1kHz. This means, that each acquisition will take at least 100ms wich might be too long for your application. NI 9237 supports rates up to 50kHz, so my first sugestion would be to just increase sampling frequency and see if it helps. 

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