Passive Components are advtrains nodes like Turnouts and basic signals.

A passive component has a state, which represents the state it is in. For example, a turnout can be either switched to the straight or the diverging branch, and a basic signal can be either red or green.

LuaATC interfaces with passive components using the getstate() and setstate() functions. Their state is represented as a string, as listed below.

All light signals that have a red and a green light can be interfaced. At the moment, these are the default red/green light signal and the tunnel wall/ceiling signals, all included in the advtrains mod.

• “green” - Signal shows green light
• “red” - Signal shows red light

Example:

-- check if the signal at (1,2,3) is green
if getstate(POS(1,2,3)) == "green" then
    ...
end

All default rail switches are interfaceable, independent of orientation.

• “cr” - The switch is set to the diverging (curve) branch.
• “st” - The switch is set to the straight branch.

Example:

-- set the switch at (2,3,4) to the diverging branch
setstate(POS(2,3,4), "cr")

The Y-Turnout and 3-Way switch use a different set of state strings based on the pointing direction:

• “l” - The switch is set to the left branch.
• “s” - The switch is set to the straight branch (only 3-way).
• “r” - The switch is set to the right branch.

The Mesecon switch can be switched using LuaAutomation. Note that this is not possible on levers, only the full-node 'Switch' block.

• “on” - the switch is switched on
• “off” - the switch is switched off

• “on” - it blinks
• “off” - it does not blink

You can assign names to passive components using the Passive Component Naming tool. These names must be globally unique in a world.

Once you set a name for any component, you can reference it by that name in the getstate() and setstate() functions, like this:

--(Imagine a signal that you have named "Stn_P1_out" at position (1,2,3) )
setstate("Stn_P1_out", "green") instead of setstate(POS(1,2,3), "green")

This way, you don't need to memorize positions.

Although not all signals usable by the interlocking system are LuaATC passive components, PC-Naming can also be used to name interlocking signals for route setting via the set_route() functions.

IMPORTANT: The “Signal Name” set in the signalling formspec is completely independent and can NOT be used to look up the position, you need to explicitly use the PCNaming tool.