square signal and strain gauge

[jujuyy]

I am inputting a square signal into my scxi 1300 terminal block and reading with the DAQ assistant.  However, i am getting a sinusodual wave output.  does anyone know why this is happening?

i am also reading pressure readings off of a scxi 1520 strain gauge block, but it's not giving me the same signal as i get off the ocsilioscope.  the signal i get doesn't show as much detail, i've tried increasing the sample rate, but i get similiar results.  anyone know why this is happening?

[Justin_M]

Hi jujuyy,

What module is the 1300 connected to?  I'm guessing that the module is actually filtering the signal you are inputting, which is basically smoothing out your square wave and making it look sinusoidal.  Depending on the module you are using, this filter could be controlled by either hardware jumpers or by software settings.

As for the 1520 signal you are seeing, can you explain how the signal looks different from the oscilliscope (or possibly take a screen shot you can post)?  Also, how are you looking at the signal?  Are you just using a test panel in Measurement and Automation Explorer (MAX)?  If so, you could try unchecking the "Autoscale" box and manually adjusting the limits of the graph, just to see if "zooming in" on the signal makes it look any better. 

Thanks,

Justin M.

National Instruments

[jujuyy]

Justin,

I've got the problems fixed.  There was a 2hz low pass filter on my board, so I just switched to a board with a 10hz filter.  And as for my pressure curve, it just turns out that I had to change some values on the map scale.  Thanks.

jujuyy