Sandustry Logic and Signals

Sandustry’s signal system is further along than most players realise, and the official record of it is not. Eight components have been written up — the ones that produce a signal, read the world, carry it and display it. The other nine are in the game and listed on the wiki, and every one of those pages is empty: seven logic gates, a Toggle, and a Repeater.

Every component, and what it is for

The three sensors are the whole trick

All three watch a 4×4 area, and choosing between them is most of the design work.

• Presence Sensor — fires while anything at all is in the box. One pixel is enough.
• Signal Sensor — fires while the box is completely full, of any mix of materials.
• Pulse Sensor — fires once, at the moment the box becomes full, and will not fire again until it has emptied and filled once more.

Read that as three different questions. Is material arriving? is the Presence Sensor. Is this buffer backed up? is the Signal Sensor. Has another batch just completed? is the Pulse Sensor.

The fullness sensors measure volume, not material. They cannot tell Gold from Sand — if you need to know what arrived rather than that something arrived, sort it with a Filter first and put the sensor on the output.

Held signals and pulses are not interchangeable

The same split runs through the inputs. A Signal Switch holds its state until you flip it back; a Signal Button sends one brief pulse and stops.

That distinction decides which one you want. A held signal is for gating something open for as long as a condition lasts. A pulse is for triggering a one-shot action. Wire a button where you needed a switch and the thing you opened closes again immediately.

What the documented half actually gives you

Read the eight written-up components together and a pattern falls out: they cover observing a factory, not controlling one.

Every documented sender has somewhere to go, and exactly one documented destination. The Signal Lamp is the only component whose behaviour on receiving a signal is written down — it lights up, and it accepts more than one incoming link. So the circuit you can build entirely from documented parts is an instrument panel:

• A Presence Sensor at the end of a line, wired to a Lamp tells you from across the factory whether material is still arriving.
• A Signal Sensor on a buffer, wired to a Lamp tells you that the buffer has backed up.
• A Pulse Sensor on a container, wired to a Lamp blinks once each time the container tops out.
• A Buffer extends any of those runs past the reach of a single link, unchanged.

That is a real payoff — those are the three questions you cannot answer by looking at one screen — but notice what it is not. Making the factory respond means a signal reaching something other than a lamp, and no official source describes what any other building does when a signal arrives. This page will not invent one.

The gates are listed but not written

The official wiki’s index names nine more components — the seven logic gates, a Toggle (T-FlipFlop), and a Repeater. Every one of those is a red link: the page is listed, and the page is empty.

They are in the table above because you will see them in the game and it is worth knowing what is there. What this page will not do is tell you how they behave, because no official source does. When that changes, this page changes with it.

There is a second gap worth naming. The research tree contains no logic components at all — not one of the seventeen appears in it, so this page can give you no unlock costs. That is the official record being silent, not an omission on our part.

Related

• Sandustry Filters Explained — sort material before you sense it
• Sandustry Factory Layout — where the machines go in the first place
• Sandustry Blueprints — once a wired section works, stamp it out