Measuring Digital Output from 3 Hall Effect Sensors

[TylerJO]

I'm working on a project where I need to map the digital signal coming from 3 hall effect sensors, plugged into the first three channels of a NI 9402 installed in a NI cDAQ-9172 chassis (slot 5).  I've done plenty of analog signal measurements before but this is my first time trying to map a digital one.  I'm trying to measure the signal at the fastest possible rate (20MHz is what NI 9402 is capable of) and I cannot get the signal to record in any way that I could analyze it.  At this point all I'm looking for is a way to record the signal at 20MHz and look at a plot from the three sensors.  We're essentially just checking how quickly the signals are being sent to the sensors, so I need to be able to record it and zoom in to see all the 1's and 0's.

I'm also doing this in signal express which may or may not be the whole problem.  To me it seems like a simple task, so I assume I'm just missing something obvious.  I got 3 digital signals, I want to record them at 20Mhz and then be able to look at the plots afterwards. I don't even want to really analyze them yet, just want to be able to zoom in and see the high's and low's from each sensor.  The test I'm recording takes about 7-8 seconds.  So far when I try this it looks like it reads the signal in the preview screen but if I try to look at the data afterwards there's nothing there to see. If anyone could point me in a direction to look or has an idea it would be extremely helpful.  If more information is needed I can get it for the board.  Thanks.

-Tyler

[Joshua-B]

Hi Tyler,

Are you pressing the Record button to log the data?