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PXI DAQmx trigger level

Hello,

 

I am using a PXIe-6124 4CH simultaneous sample card. The sample rate is set to 4Ms/sec and the range is -10 to 10V. The AIs are all set to voltage. I'm using one of input CHs to trigger the card and collect my pre-samples and post-samples. The issue I'm having is that I'm trying to trigger off a 25mV voltage pulse. I set the trigger level anywhere from 10mV up to 20mV and I cannot get the card to trigger. 

If I use another pulse that has an 80mV amplitude, then the card does trigger (with the trigger set to 20mV. I did not try a lower trigger level). So, the question is whether there is a minimum AI amplitude for generating a trigger? The specs don't specify this.

Note: There is no grounding issue, when I trigger the card with the 80mV pulse, I can capture the 25mV pulse and plot it correctly.

Thanks.

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From page 8 of NI 6122/6123 Specifications

ZYOng_0-1710286798505.png

 

For input range of +/- 10V, the smallest voltage is 20/(2^8-1) = 0.078 V 

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Control Lead | Intelline Inc
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