V00 - no MDB signal
Check MDB cabling, whether cashless is enabled on the vending controller, and whether the reader is set to the correct machine protocol.
V01 - VMC side inactive
The MDB connection exists, but the vending controller has not initialized the reader correctly.
V02 - reader disabled
The vending controller has explicitly disabled cashless. Door/service states, pending cash credit, or controller behavior can cause it.