Stacking PXI 4110 power channels and sharing ground with other PXI 4110 cards

[adams156]

I need to use a PXI 4110 power card to generate a 28V 1A voltage source.  I read this article http://www.ni.com/example/30356/en/ to find out how to accomplish that by stacking channels on a singular card.  My problem is that I have 2 other similar cards that do not stack channels but all cards connect to a circuit board, and they all end up sharing the same ground.  Will my stacked card's configuration adversely affect the ability of my other cards to produce their required voltages due to the shared ground?

I also looked at http://digital.ni.com/public.nsf/allkb/F0893906EF4C08EE8625727A006DD89B?OpenDocument but I'm not sure that offers a better option either.

[Richard_Smith]

Hello,

Since CH1 and CH2 are isolated outputs, I think there should not be any problem if you connect the negative terminals from the rest SMUs together.

Regards,

Richard.

[adams156]

Thanks for the response! It helped me realize what my misunderstanding was. Let me elaborate some so that you can correct me if I'm wrong.

I didn't realize at first that the power card has two separate ground terminals. Even the icon for the CH0 ground is different from the icon for the CH1/CH2 ground because the CH0 ground is true ground and the CH1/CH2 ground is floating. The voltages that are set programmitically for CH1 and CH2 are not automatically relative to true ground like I originally thought. If I programatically set CH2 to -20V and then connect the -20V terminal with the true ground, that will bias the CH1/CH2 floating ground up to +20V relative to true ground.  At this point, I can programatically set CH1 to a voltage between 0V and +20V which will result in an output of +20V to +40V because the floating ground has been biasedt to +20V already.  The other power cards are not supplying anything over 20V, so all of their floating grounds and true grounds are wired together.  I'll just have to make sure not to connect the CH1/CH2 floating ground to any of the ground terminals on the other power cards.