Presumably: FPD refers to the readers/gates used to touch on/off, and TDC/BDC refers to the gate attendant's console that sits besides some gate arrays.
FPD: As i mentioned in my first post in this thread, Fare payment device. The device you hold your card against to touch on and off. Comes in Stationary, mobile, and gate variety's but all do the same thing.
BDC: Bus driver console. This is the device next to the driver that they log into with an operator card to select a shift/route and used to add credit to patron cards among other things.
TDC: Tram driver console. Similar to a bus except there is a primary and secondary device due to a tram having two cabs.
Unless a driver is logged into a BDC/TDC the FPD's do not become active on that particular vehicle and therefore you will not be able to touch on/off. This should be clear as day to an AO and can be easily verified by time stamps and status in the back end. An FPD at a fixed location (station) should always be active except during maintenance or failure.
The console that sits beside some gate arrays that you mentioned is called a GAC, which is short for Gate attendant control or Gate access console depending on who you speak to.
@YM-Mundrabilla, If I come across some lingo, a component, location, whatever, on this forum or others that I don't know the meaning of or what or where it is, I don't get upset, I show some initiative and try and find out for myself. And if I can't find out I politely ask the person to explain it a bit better. A simple google search which would have probably taken a fraction of the time it took you to type your post would have revealed the answers for you with even having to click on a link. If that isn't enough there are even links back to existing Railpage threads which explain what they are. I did not use the abbreviations as a show of knowledge or arrogance or any other way you wish to spin it, I simply did it out of habit and the fact that that is what anyone who deals with them calls them. You can lead a horse to water.........