Maximum Working Voltage and Input Range

[David_M97]

Hi guys, recently I started to work with DAQ devices, specifically USB 6215. I need to measure high voltages, between 12 to 19 VDC. Somebody told me that I can measure until 20 VDC if I connect the (-) pin to ground in differential mode. However I think that this will violate the maximum working voltage of ±10.4 V related to AI GND but I am not sure if this one applies for the differential mode, if not which is the criteria to determinate maximum voltage for a measurement?


I dont understand well what is the difference between the maximum working voltage and the Input range? Which would be the maximum voltage that I can measure if I connect the (-) to Ground in the differential mode?


I hope you can help to solve my doubts, I am new using DAQ devices and I would like to get more information for in the future I can take right decision when I use the equipment.


Thanks in advance.

[Machop]

You can use for 20V inputs if you are not using more than 2 channels 

[crossrulz]

What you want is to connect 10V to AI GND.  Then the - to the GND of the system.  The key is that you need each side of the diff measurement to be within 10V of AI GND.

[David_M97]

Hi Machop, Crossrulz, first of all thanks for their answers.

@Machop: Why do you say that the limitation are 2 channels?

@Crossrulz: I did not understand well this part "What you want is to connect 10V to AI GND. "  could you please explain me more?

Thanks to both, the forum is a really good place to learn more about NI technologies.