They probably activated VNS but not with RadarPC. It's a software switch.
RS-422 is not a protocol -- it's a different electrical signal than RS-232. RS-422 uses differential signal pairs to toggle between states -- each pair of wires represents a single signal. RS-232 uses a single wire for each signal, toggling voltage with a reference to "ground" state.
I don't know how that BYTECC device can handle both, because it requires different chips and pin configurations, but I'm glad to hear you got it working.