Scripting Examples

Scripting Examples

Paste an example into the Logic Terminal, press Save, then Run. Directions ("up", "north", …) are relative to the Logic Bus; change them to match your build. Item ids are 1.20.1 ids.

1. Import everything from a chest

var chest = side("up");

function tick() {
  if (chest) chest.pull();      // any item, as many as the budget allows
}

2. Import only some items

var chest = side("up");
var wanted = ["minecraft:iron_ingot", "minecraft:gold_ingot", "minecraft:diamond"];

function tick() {
  if (!chest) return;
  for (var i = 0; i < wanted.length; i++) {
    chest.pull(wanted[i]);
  }
}

3. Keep a machine stocked

var machine = side("north");

// Top up `id` in `ep` until it holds `amount`.
function ensure(ep, id, amount) {
  var have = ep.count(id);
  return have < amount ? ep.push(id, amount - have) : 0;
}

function tick() {
  if (!machine) return;
  ensure(machine, "minecraft:coal", 16);
}

4. Stock keeper with autocrafting and a cooldown

Without a cooldown the script would order the same craft again and again while the first order is still running.

var targets = [
  { id: "minecraft:stick",    min: 64,  batch: 64 },
  { id: "minecraft:torch",    min: 128, batch: 64 },
  { id: "minecraft:iron_block", min: 8, batch: 4 }
];
var lastOrder = {};            // id -> game time of the last order
var COOLDOWN = 20 * 60;        // 1 minute

function tick() {
  for (var i = 0; i < targets.length; i++) {
    var t = targets[i];
    var last = lastOrder[t.id];
    if (last !== undefined && time() - last < COOLDOWN) continue;
    if (net.count(t.id) < t.min) {
      var crafts = net.craft(t.id, t.batch);
      if (crafts > 0) {
        lastOrder[t.id] = time();
        log("ordered", t.batch, t.id);
      } else {
        log("cannot craft", t.id);
      }
    }
  }
}

5. Sort a chest: ores and wood to separate chests, the rest to the network

var input = side("up");
var ores  = side("west");
var wood  = side("east");

function tick() {
  if (!input) return;
  var stacks = input.list();
  for (var i = 0; i < stacks.length; i++) {
    var id = stacks[i].id;
    if (ores && /_ore$|^minecraft:raw_/.test(id)) {
      input.move(ores, id);
    } else if (wood && /_log$|_planks$/.test(id)) {
      input.move(wood, id);
    } else {
      input.pull(id);          // everything else goes into the network
    }
  }
}

6. Overflow protection

When free space gets low, dump junk into an overflow chest so the network never fills up.

var overflow = side("down");
var junk = ["minecraft:cobblestone", "minecraft:dirt", "minecraft:gravel",
            "minecraft:cobbled_deepslate", "minecraft:rotten_flesh"];
var alarm = false;

function tick() {
  var low = net.freeBytes() < 2000;
  if (low !== alarm) {                 // log only when the state changes
    alarm = low;
    log(low ? "LOW SPACE: " + net.freeBytes() + " bytes free" : "space OK");
  }
  if (!low || !overflow) return;
  for (var i = 0; i < junk.length; i++) {
    overflow.push(junk[i], 256);
  }
}

7. Round-robin feeding of two machines

Global variables survive between runs, so a counter can alternate targets.

var machines = [side("east"), side("west")];
var turn = 0;

function tick() {
  var target = machines[turn % machines.length];
  turn++;
  if (target) target.push("minecraft:raw_iron", 8);
}

8. Throughput meter

Logs how many items per second flow into the network.

var ITEM = "minecraft:iron_ingot";
var lastCount = null;
var lastTime = 0;

function tick() {
  var now = net.count(ITEM);
  var t = time();
  if (lastCount !== null && t > lastTime) {
    var perSecond = (now - lastCount) / ((t - lastTime) / 20);
    log(ITEM, perSecond.toFixed(2) + "/s");
  }
  lastCount = now;
  lastTime = t;
}

9. Balance two chests

Evens out a specific item between two chests by moving items directly from the fuller one to the emptier one.

var a = side("west");
var b = side("east");
var ID = "minecraft:cobblestone";

function tick() {
  if (!a || !b) return;
  var ca = a.count(ID), cb = b.count(ID);
  var diff = Math.floor((ca - cb) / 2);
  if (diff > 0) a.move(b, ID, diff);
  else if (diff < 0) b.move(a, ID, -diff);
}

10. Self-diagnosing script

Wrap the work in try/catch to keep running through ordinary errors (such as a mistyped item id) and report them.

var chest = side("up");

function tick() {
  try {
    chest.pull("minecraft:iorn_ingot");   // typo: throws "unknown item"
  } catch (e) {
    log("problem:", e.message);
  }
}

Budget errors (instruction, time, call limits) cannot be caught, they stop the bus.