What a rung is, and how conditions, timers, counters, latches and priority decide which one is live.
The ladder
A ladder is a list of rungs. A rung is one rule:
{
"id": "cold-hold",
"priority": 12,
"family": "survival",
"when": {"cold": {"ton": {"outdoor_temp": "<-10"}, "hours": 2}},
"then": ["build a heater in the barracks"],
"never": ["leave the door open"],
"latch": false,
"why": "owner: the barracks froze twice"
}| Field | Meaning |
|---|---|
id | Unique. A player copy of a preset rung keeps the preset's id. |
priority | A number; lower fires first. Live rungs are listed in this order and the first is the colony's job. Ties are a checker error. |
family | A grouping for the window's filter. |
when | The conditions. Every key must hold for the rung to be live. |
then | The steps, in order, in plain words. Each names the tool or command that does it. |
never | What this rung must not do, however the steps are read. |
latch | When true, the rung stays satisfied once it has fired, until its own reset. |
why | Why the rung exists -- usually the words of whoever asked for it. |
Conditions
A key is a sensor (colonists), a mark (mark_camp_stable), a tag inside braces ("<{STEEL_RESERVE}") or a definition read on demand (count_Steel, research_Gunsmithing, alert_HunterLacksRangedWeapon). A value is:
| Value | Holds when |
|---|---|
true / false / a number | the reading equals it |
">0", "<3", ">=1", "<=2", "!=0" | the comparison holds |
"<{FOOD_MIN_DAYS}" | the comparison holds against that tag's current value |
A missing reading never fires. If the game cannot give freezer_temp (no freezer, or the mod that measures it is absent) the contact shows amber and the rung stays quiet. It does not become zero and it does not become true.
Instructions
An object as a condition value is an instruction, named for the PLC instruction it copies:
| Instruction | Form | Holds when |
|---|---|---|
any | {"any": [{"corpses": ">0"}, {"designations_hunt": ">0"}]} | at least one listed condition holds (OR) |
not | {"not": {"held": {...}}} | the inner condition does not hold |
ton | {"ton": {"outdoor_temp": "<-10"}, "hours": 2} | the inner condition has held continuously for that long (on-delay; ticks or hours) |
tof | {"tof": {...}, "hours": 1} | the inner condition held within the last that-long (off-delay) |
ctu | {"ctu": {"mark_store_tried": true}, "preset": 2, "reset": {"food_store": true}} | the inner condition has gone true that many times since the reset condition last held (count-up) |
ons | {"ons": {"threat_letter": true}} | the inner condition went true on this scan (one-shot, rising edge) |
Instruction memory -- how long a ton has held, how many times a ctu has counted, whether an ons has fired -- moves on tick scans only and is saved with the colony.
A common pattern: a rung tries a step, and a fallback rung with a ctu on a "tried" mark takes over after two or three refusals:
{"colony_exists": true, "mark_shelter_set": false,
"shelter_tries": {"ctu": {"mark_shelter_tried": true}, "preset": 2, "reset": {"mark_shelter_set": true}}}Marks and tags
Marks are what the game cannot measure and someone records on purpose: mark_camp_stable, mark_raid_kind (1 walk-in, 2 drop pods at the edge, 3 drop pods in the centre, 4 siege, 5 sappers, 6 manhunter pack, 7 mechanoids, 8 infestation, 9 tribal swarm, 10 pirate gunline), mark_gate_sections_done. A boolean never set reads false. Where a sensor later replaced a mark, the sensor's catalogue entry names the mark as its fallback and the mark is read only while the sensor is unmeasured.
Tags are numbers with bounds. Variables (FOOD_COMFORT_DAYS, STEEL_RESERVE, COLONIST_TARGET) can be overridden within min..max; constants are the owner's safety limits. A rung reads one as {NAME} inside a comparison.
What a live rung does
- It is listed, first one first, in the Ladder tab and in
read_ladder. - On its rising edge, with Notices on, its notice is posted as a game message.
- If it is switched to auto, its coils run:
message,set_markorset_tag. That is the whole list. RimPLC never drafts a pawn, places a blueprint, forbids an item or calls a trader.
The then steps of the shipped preset name concrete actions -- arm the colony, put a cooler in the freezer wall, add a meal bill, pick the next research project. They are written for an external assistant acting through another mod's automation file; without one, they are advice, and the Ladder tab shows which steps a present client could carry out and which have no answer in the loaded mods.
The shipped ladder
Presets/LadderV2.json carries the whole book: a camp on landing (store over the supplies, walls and a roof around them, a shelter, a stove and a meal bill, then exploring), weapons and self-tend checked every scan, threat letters read the turn they land, hunting and butchering, the freezer, research order, defence, trade, animals, the mountain base, Royalty, Ideology, Biotech and Anomaly, the ship. Families and counts are in the window's filter; the why on each rung says where it came from.