The nIO D device allow you to control either non Acuity fixtures or Acuity fixtures that are not nlight enabled.
The nIO EZ PH that is embedded in an Acuity Fixture (thus making it nLIGHT enabled) with an eldoLED driver, will allow the driver to enter a sleep mode rather than powering completely off. The advantage of the sleep mode is that the fixture will ramp up more quickly and initialize because it is not completely powered down. Non eldoLED Fixtures do not accomplish this.
The sleep mode is dimming the control down to 0.3 VDC.