If you have advanced to the point of using switches and triggers, read on.
(Note: I assume you have loaded ConVict and done other necessary preparation, so they are not covered here.)
Basicly the ControlDevice (CD) triggers an event in its target. If you were to add CD-link from a switch to a door, it would cause the door to open when the switch is pulled.
I. First things first: What is a link?
Link is basicly a link between two objects. There are many different kind of links - some can be used to give items to guards, some make guards to walk around and some trigger events. The DromEd tutorial gives you the basic idea of what a "link" is.
Adding a link:
Create a room with a switch and a door. Now check the door's ID (a number in brackets) and write it down (Later when the map gets bigger, you will need to write down these number quite often, and its very handy to keep a pen and a paper near by). Next select the switch and click "links". Click "add" and choose ControlDevice from the list. Type the ID number of the switch on the upper field and the ID of the door to lower field. Basicly that's it. Now the door opens and closes from the switch.
II. Next thing second: What is a script?
Thief uses scripts to accomplish various tasks. Door uses a script called "StdDoor", button use a script "StdButton". Lights that can be turned on or off from a switch uses "AnimLight". Conversation "TrapConverse". Books can be read with "StdBook". Are you even a bit confused? Good, you should be. There are numerous scripts that do different tasks and there is no list of scripts available, so search the real missions or wait till someone does a good tutorial/list. Basicly the script is the heart of the object. Add "StdDoor" to a book and you got yourself a book that works like a door. (Then there is the FrobInfo and other small systems that may prevent a script from working, but I will not cover that here, maybe later.)
When player goes near the Bafford's front gate, the guards start to talk about bears. It is done by a simple script called "TrigRoomPlayer". Once again, make a room and create 2 different room-brushes in it, separating the room from the middle. Do not leave any area not covered by the room brushes. Build the room database. Select other of the room brushes and click "create" and from there "Add". (be at the root of the room-tree when you create the new room) Type in a name, ie. "TriggerRoom". And yes, it is a concrete room when DromEd asks you. Check for sure the room is now the TriggerRoom. If it is not, click "create", select TriggerRoom and click "create". (Sometimes you can't see the change immediately, so select something else and then the roombrush again.)
Now click "Edit" -> "Add" -> S -> Scripts. Type "TrigRoomPlayer" to field "Script 0". Hit OK and Done. Now create a porcullis from Physical -> Terrainlike -> Doors -> slidy_door -> porcullis -> select one of them. Create the porcullis and check it's ID. Select the TriggerRoom room brush and click links. Add a ControlDevice from the roombrush to the porcullis. Build room database and all the other things. When you enter the TriggerRoom, the porcullis should open and when you leave the area, it closes.
More advanced things:
Inverter that can be found from "fnord -> TrapTrig -> Inverter", can be used to invert the effect of ControlDevice. Using the the same room, where the porcullis is, create an inverter. Now link the inverter to the porcullis and the TriggerRoom to the inverter with a ControlDevices.
Remove the CD-link from the TriggerRoom to the Porcullis. Now the gate
opens when you are NOT in TriggerRoom.
More practical usage if the Inverter can be found from doors. If you want a door that closes when another door opens from a switch, you have to use an inverter to accomplish this.
I think I've confused everyone's head enough and shut up for now. Just remember, that it is all logical. Once you understand the basics, it really is quite simple. And yes, I know I'm not much of a tutorial writer.
Comming up next: What makes a guard tick or Scripting your way to