Fwd N Rev... Why? To park, headlight on, smoke working, whistle before movement, or for an operating car to get power for it's action without the loco running off.
PS DCC system output to your rails is neither DC or AC voltage. Said meters do not give you an accurate reading. It is DCC. You need a meter that can read DCC.
To be accurate, it is some form of AC or DC (pulsed). No way around it.
A serial data transmission who's signal is based on the frequency of a change in signal is more accurate. It piggy backs the motor power or via. Radio waves.
Edit was,made to " without" the loco running off