PXIe-6363 Voltage Measurements

[Dan_Lopez]

Hi Guys,

First post here. I tried to search the documentation first but came up empty.

I'm using the analog inputs on the 6363 card to make some voltage measurements. I have 2 questions:

1. I know the channels are limited to +/- 10 volts for the inputs. I have a 25 volt line with a series current sense resistor (50mOhm). I want to make a differential measurement across the resistor using 2 of the analog channels. The actual voltage across the two points will be in the mV range but the single ended voltageon each will be ~25 V. Will this work?
2. In a similar setup but on a 5 volt line can I make a differential measurement across a current sense resistor using 2 of the channels and then turn around and use one of those same channels to make a single ended measurement wrt gnd?

Thanks for your help!

[crossrulz · Accepted solution]

There is a line in the data sheet that states

Maximum working voltage for analog inputs (signal + common mode)

±11 V of AI GND

So with a common mode voltage of 25V, you will hurt your card.  The 5V line should be fine.

If you look at Digikey, there are chips specifically made to sense a current shunt.  The amplifiers will turn the differential voltage into a single ended relative to ground.

[Dan_Lopez]

Thanks. I figured this was the case. I was already looking into using differential amps for the current sense resistors anyway.

[dwelty]

Similar issue here:

I inadvertently sent 30V to one of my analog inputs on the 6363. What will this do to my card?

[USBarnes]

dwelty,

The effects of 30V on an input channel to your device could vary depending on how long 30V was applied to the input and the current that came with it. If it was very brief, you may not see any side-effects, however if this voltage was sustained for a longer period of time then some components could have been damaged. Additionally, if the current exceeded the maximum specifications for the device, then damage could have been caused to internal components.

[diepni]

Hi NI Community,

I'm working on the instrument controlling software for the PXIe-6363.

We are  using MS. Visual Studio, C#. I would appreciate it, if any one of you send to me the sample code in C#.

Thank you;

Adam Nguyen

anguyen@pdseng.com