The cRIO is capable of drawing 20W, but usually draws about 10W.
The DSC is capable of drawing 45W, but usually draws less than a tenth of that. The unloaded use is close to zilch, as it is just a few LEDs and some simple logic. The real load is what you attach to it - Servos, mostly. To eyeball it, total up your outputs and assume 90% efficiency in the switchers. Then add a little margin on that for the LEDs.
Both of these use switching supplies, so Watts is the correct unit to work in.
If you are interested, the
datasheet and
schematic for the digital sidecar are posted. It will be probably be easier to just measure the draw.