Solution:

1. DIGITAL a) The DO on the NA & NB models are Sourcing (PNP). These outputs will source the DC voltage of the same value that is being used to power the radio. b) The DO on the NC & ND models are Sinking (NPN). These outputs require a DC power supply be connected in series on the output to sink the voltage. 2. ANALOG a) The AO on all models when configured as voltage (0-10 VDC) are Sourcing. These outputs will source the 0-10 VDC directly to the end equipment. b) The AO on all models (except ZZ-4AO-2) when configured as current (0-20mA) are Sinking. These outputs require a DC power supply be connected in series on the output to sink the voltage.