How to Use Controllers and Sensors

What the controller system does

Scrap Mechanic’s controller system lets you wire any functional block to any other functional block. A sensor detects a state change (motion, raycast hit, timer), a controller interprets it, and a functional block (light, thruster, gate, weapon) reacts. With three blocks you can automate almost anything in the game.

The five core sensor types

• Motion sensor — Detects entities in a 5-block radius. Use it for base alarms and turret triggers.
• Raycast sensor — Fires a virtual ray and detects what it hits. Use it for laser tripwires and auto-doors.
• Timer sensor — Fires every X seconds. Use it for blinking lights and resource conveyors.
• Button — Manual trigger. Use it for cockpit controls.
• Logic gates — Combine multiple sensors with AND/OR/NOT logic. Use it for advanced behaviour.

How to wire a sensor to a block

1. Hold F with a controller selected.
2. Click the input block (sensor, button, timer).
3. Click the output block (light, thruster, gate).
4. Confirm with the green check mark.

The connection is now live. Trigger the input and the output reacts. You can chain multiple outputs to a single input, which is how most base alarms work.

Five automation patterns you can build today

1. Auto-door

Wire a Raycast sensor pointed at the door to a Logic gate set to NOT. Connect the NOT output to the door’s open input. The door stays open only when no entity is detected, which is wrong — flip the logic and you get an auto-door that closes when you approach.

2. Raid alarm

Wire a Motion sensor placed above your base entrance to a Siren block. Add a 2-second timer to the siren so it does not get stuck. Now every Totebot triggers a loud warning.

3. Spud Gun turret

Mount a Spud Gun on a bearing. Wire a Motion sensor to a Logic gate, then to the Spud Gun’s trigger and the bearing’s rotation. The bearing spins slowly, the sensor detects a non-mechanic entity, the gun fires.

4. Conveyor sorter

Wire a Raycast sensor to a Conveyor’s tilt function. Crops of the right type pass over the sensor and the conveyor routes them to the Cook Bot input. This is the basis of any auto-farm.

5. Headlight timer

Wire a Timer sensor set to 2 seconds to a Headlight. The lights blink in a pattern that scares off most Totebot raids before they begin.

Wiring tips from the community

• Name your sensors in the wiring menu. Once you have 20+ connections, names like “Front Door Sensor” save hours of debugging.
• Use Logic gates aggressively. They look intimidating but they are the difference between a build that works once and a build that always works.
• Avoid wiring more than 10 outputs to a single input. Older versions of Scrap Mechanic had a soft cap, and the 1.0 patch did not raise it. Split heavy automations across multiple sensors.

For the broader context on how these automations plug into base defence, read the defensive base layout guide.