DSC-BRAIN USER GUIDE · HOW IT WORKS
When the brain stops: the hub and the plugs
The brain is the Raspberry Pi that runs the dashboard, the plans and the logs. This page says what still happens if it stops, and what does not.
● Running on our test kit: 9.10.0 · kit firmware 9.0.0.0 · last report 22 Oct 2026
On this page
What the hub keeps doing
The hub keeps running its wired fans and dimmed lamps from its own sensors and its own clock, inside its hard limits. It does not need the brain to do this: the temperature and humidity sensors wired to it (the main tent, the room and a second, smaller tent) and its CO₂ input are read by the hub itself.
The hub cannot switch the smart plugs. The brain does that, so what a plug does when the brain stops is set by the plug itself (below).
The hard limits
These two limits are in the hub's firmware. They apply whether or not the brain is running.
| When | What the hub does |
|---|---|
| Tent temperature reaches 35 °C (clears below 34 °C) |
The outside exhaust and both intakes run at 100 %, the room-only exhaust is off, and the lamp is off. The hub stops asking for heat and humidity. The fans go back to their earlier levels once the tent is below 34 °C. |
| No valid tent temperature for 3 minutes | The hub stops asking for heat and humidity, runs the outside exhaust at 40 % and the other three fans at 25 %. |
What each smart plug does
The four Sonoff smart plugs (heater, heat mat, humidifier and dehumidifier) each start off at power-on, and each switches itself off if it has not heard from the brain for its own time:
| Smart plug | Starts at power-on | Switches itself off after it last heard from the brain |
|---|---|---|
| Heater | Off | 60 seconds |
| Heat mat | Off | 90 seconds |
| Humidifier | Off | 90 seconds |
| Dehumidifier | Off | 240 seconds (4 minutes) |
What is not covered
A Tuya plug holds its last state when the brain stops; a Zigbee plug likewise has no hub cut-out behind it. That is why the four climate appliances stay on the Sonoff plugs above.
The hub is optional, and you can start without it. A kit with no hub has none of this: no wired fans or dimmed lamp from the hub, no 35 °C limit and no sensor-fault mode. With plugs alone, nothing takes over if the Pi stops. Don't leave a heater unattended on plugs alone; the hub adds that failsafe.
What is planned
A hub failsafe that holds the brain's plan is planned. The authority split today is in Who decides what: hub vs brain. It is not switched on. See What runs today and what is coming.
If your hub or plugs have stopped reporting on your kit, start at Hub offline or not reporting or Plugs and appliances: not reporting, mismatch, ineffective.