Beyond Voltage Limits on USB 6008?

[buckidge]

I'm using a USB 6008 to measure differential analog signals within the range of 3-5.3 V. I choose this range, because outside this range, I'm not interested in what the voltage is, just knowing that its 'on the rail', but using all the ADC's resolution in that range. 

So in feeding in a signal of ~0.05 V, I was expecting to read 3V, telling me that the voltage is below 3V, but yet it returns 0.05V?

As this was unexpected for me, could someone please explain what I can/should expect of my USB6008's responsed to signals that are out of the prescribed range? Is there some 'rollover' effect? Should it return the value at the limit? Does it depend on how far past the limit it is?

Thanks for your help!

[Dennis_Knutson · Accepted solution]

The range inputs do not function the way you think. You specify the range you expect the signal will be within and the DAQmx driver will set the most appropriate range that the device supports. The actual ranges are listed in the manual. In your case, because you specify a max of 5.3, the device would be set to the +/-10 volt range.