analog output ground loops

[hvo123]

Hi Carisa/Lynn,

The reason I want to float the source is to eliminate ground loop noise.  Right now with AO0 referenced to AO GND (same as AI GND, I/O GND), i am creating a ground loop with the power supply's GND.  And I cant change the power supply.

Does it not work because my AO0 is set to 0V?  If AO0 is 0.5V or 1V, then will it work? 

I am trying to follow the Field Wiring and Noise Considerations for Analog Signals guideline, what can I do to avoid the "Not Recommended" conditions in this guide?

Thanks

Best Regards

HV

[johnsold]

HV,

The reason it does not work is that both AO signals are referenced to AO Gnd.  Think of them as two batteries.  The negative end of each battery is connected to AO Gnd. The positive ends are the two outputs.  It does not matter what voltages are set on AO0 and AO1.  They are both still connected to ground.

Examples of floating sources are a battery with no connection to ground or a power supply derived from a secondary of a transformer in which no part of the secondary side circuit is connected to ground.

Lynn

[hvo123]

Lynn,

I see your point.  In my case, I'll have to live with the ground loop noise. 

Thanks

Best Regards

HV