Motion Sensor

The motion sensor is the switch for everything that should only run while somebody is around: corridor lights, door openers, a note on a display. It mounts in the 0.5 m grid on a wall, floor or ceiling, needs no power according to the game data and has one shared port for power and data.

What it covers: according to the game code it watches exactly one large cell – the 2 × 2 × 2 m cube it sits in. It remembers every movable object that enters this cell and drops it again as soon as it leaves. That means player characters, but also loose items: if somebody drops something there, the sensor stays triggered until it is picked up again. What somebody carries in hand or inventory does not count separately.

• Activate is 1 while at least one object is in the cell, otherwise 0. The sensor keeps setting this value itself; whatever you write into it is overwritten right away.
• Quantity is the number of objects it currently tracks in the cell.
• On can be read and written. The detection in the game code does not check On, though – do not rely on a switched-off sensor staying quiet.

For a long corridor you therefore need several sensors, one per 2 m section. Give them all the same name and read them with batch mode 0: the average of Activate is above 0 as soon as somebody is anywhere along it.

It is built from the Kit (Sensors), which also builds the gas, daylight, occupancy and proximity sensors. If you need an adjustable range, use the Proximity Sensor; for a whole room, the Occupancy Sensor.

A proven pattern is the light with run-on: every detection resets a counter, and the light stays on until it has run out – 60 ticks for 30 seconds, for example. If the sensor is missing, lbn returns NaN; then it is better to leave the light on. The complete program is in Sensors: gas, daylight, motion, occupancy.