Problem with CDAQ ADC timing Mode

[rCorvec]

Hello,

My purpose : Acquire strain gage signal with cDAQ 9132 and NI 9219.

Configuration : Half Bridge 1

My problem is simple, my signal only change if i change the timing mode, for example in high resolution, high speed or best rejection 50 Hz. Even if i change the sampling rate from fs=50k sample=5k to fs=1k sample 100, it change nothing at all, i still have the same signal.

As you can see with the screenshot, my signal in high resolution take a point only each 500 ms.. if someone can explain the link between the sampling rate and the timing mode please. Or juste tell me if labview can only take a point each 10 ms (high speed), 110 ms (best rejection 50Hz) or 500 ms (high resolution).

Thank you.

Please fin attached my VI.

[Eloise]

Hello rCorvec,

The sampling rate of the NI C-Series Delta-Sigma modules depend on a number of factors. One of these factors is the Timing Mode that is set for the device. Each channel will have to wait for a hardware specific conversion time, and the Timing Mode will affect that amount of time. 

On the NI 9219 you can set up different timing modes. Depending on the mode the sampling frequency is different. This is because of the internal delta sigma analog to digital converter.
Please have a look at the following KnowledgeBase. These documents will explain the behavior off the card and the different setups.
NI 9219 Only Samples at 2 Hz Despite a Higher Sampling Rate

http://digital.ni.com/public.nsf/allkb/33EFB527E17AFCB68625765E007521EC

Have a good day.