Correct.
Levers and their components are binary. If you change the lever, you change the binary state (i.e. "on" or "off", "open" or "closed") of whatever is attached, so something that was open closes, something that was closed opens.
If you want to open one floodgate (or hatch, or door) and close another floodgate (or hatch or door), with the same lever, and you always want that lever to keep the two doors in opposite states, it's as simple as this:
- Build a lever
- Build your doors
- Link the first door to the lever
- Pull the lever
- Link the second door to the lever
Um... no.
These don't work like that. Ancient Enemy & Lesconrads have it right.
If you "open" a lever, a door (or other barrier)
opens. If the door is already open,
nothing happens. Similarly with closing a lever - any open doors close, but closed doors stay closed. Floodgates and hatches work similarly.
(Note that floodgates have a delay that can create problems if using pressure plates with water or other stimulus that can "toggle" too quickly, before the floodgate can achieve it's new state. Two (or more) signals may be sent, but only the first is read until the state has changed.)Drawbridge-doors* work the opposite. They
raise when "open", which shuts the path. This can be used to your advantage for computing.
(*A raised drawbridge becomes a wall, so can seal a hallway or other passage, effectively acting as a door or floodgate to seal fluid flow.)And every lever is set up the same, visible as either open or closed depending which way it's leaning (left is closed iirc, right is open - but I wouldn't be the fortress on that. It should be obvious.)
But currently there is no barrier that toggles every time a switch is thrown regardless of its state, open or shut.
(I was installing my first bank of floodgates, my first mechanisms, managed to throw the lever (to "open") before attaching any floodgates to it. They were then build, and the dorf predictably sealed himself on the wrong side. I then connected a mechanism, and threw the lever (to "closed" - but I didn't realize this yet) to release him - nothing happened.
There was mixed frustration and panic, and only some time later I figured out what had happened.
Levers don't toggle the barriers they are connected to. They send them either an open or close signal, according to the state of the lever, and they respond accordingly.