Hello commkruge,
You will let to let know your name.
You will need to wire up the wallbox with a 28/30 volt supply , most people do this via a wallbox transformer.
Connect the 28/30 volts onto the interface but check which is the common connection. The cable for the 28 volts from the interface to the wallbox should be heavy duty dependant on the distance of the cable the clock & data can be thin cable There used to be suppliers of cables that did a multicore cable with two thicker cores which was ideal.
You may have to link logic common to the common connection to get the wallbox to work.
The WRD Mon will stem from an earlier age where the transformer had a relay in it to stop more than one signal comming down line in a multi wallbox invironment such as in the electromechanical jukeboxes that used 28volts, common, AC control and Signal.
Regards
Alan
Alan Hood
ami-man
UK