How to ground ni-usb-6009

[uoprummel]

I have an NI usb-6009 daq.  On the digital side, I have P0.0-P0.3 going to a stepper motor driver that runs on 12 VDC, P1.0-P1.3 going to another stepper motor driver also running on the same 12 VDC power supply.  On the analog side, I have AIO+ and - connected to an LVDT that is running on +/-15 VDC from a separate power supply.  Then I have AI1 + and - connecting to an amplifier, which is amplifying a signal from a wheatstone bridge.  5 VDC is connected to the wheatstone bridge, and +/-15 VDC to the amplifier.

So according to my voltage sources:

I have a microprocessor that can provide both 5 VDC and 12 VDC...

Microprocessor:

5 VDC - Wheatstone bridge & stepper motor drivers (Is it okay to have the wheatstone bridge connected to the 5VDC source at one terminal, and ground the other terminal, or do I need to provide +2.5V and -2.5V?)

12 VDC - Stepper motor drivers

Power supply:

+/- 15 VDC - LVDT & amplifier

I'm not sure where I ground what on the NI-6009.  I see a ground on the digital side, and multiple grounds on the analog side.

Thanks for your help!

-Nick

[Tom__Sedlack]

From the USB-6009 manual:

 Ground—The reference point for the single-ended AI measurements, bias current return point for differential mode measurements, AO voltages, digital signals at the I/O connector, +5 VDC supply, and the +2.5 VDC reference

A quick ohm-meter check can verify they are all connected.