PCI-6220 Differential Measurement, AI Sense and AI GND

[chassan]

Hello,

When measuring differentially using a PCI-6220, what sould the AI Sense and AI GND be connected to...e.g. The cahssis of my system?  Each other? Somewhere else?

I have reviewed the measurement connection diagram (somewhere on the ni.com website).  It shows the +/- connections for differential measurements, but it doesn't show what to do with the AI Sense and AI GND connections.   

Thanks for any assistance.

Chris

[S_Hong]

Hi chassan,

When taking differential measurements on a PCI-6220, you only need to make the +/- connections and there is no need to connect AI Sense nor AI GND. These terminals are only used when taking single ended measurements as shown in Table 1 in the field wiring diagram.

https://www.ni.com/en/shop/data-acquisition/measurement-fundamentals/field-wiring-and-noise-consider...

Hope this helps,

S_Hong

[chassan]

Hi S_Hong,

Thanks for the reply.

However, do "best practices" say that I should just leave the AI GND and AI SENSE terminals on my NI 68-pin break-out card open or should I connect then to chassis, each other, or something else?

Thanks,

Chris 

[S_Hong]

Hi chassan,

There is no need to connect AI GND as it is already internally connected to the same ground as your computer. Connecting another ground may lead to ground loops which might affect some measurements. As for AI SENSE, there is no need to connect this terminal unless you are going use it to do single-ended measurements.

S_Hong

[chassan]

S_Hong,

Thanks for all the assistance; that is exactly what I needed to know.

Best Regards,

Chris