====== Design Principles ======

===== Safety: 24V SELV Recommended =====

We encourage building the entire room installation on **24V SELV** (Safety Extra-Low Voltage per IEC 61140). This is the recommended approach for maximum safety and simplicity.

In a typical escape room build, it is not only electricians who work around the wiring. Set designers, painters, and decorators routinely move, reroute, or work in close proximity to cables while constructing and modifying the scenography. With 24V SELV, this is inherently safe — there is no risk of electric shock, even if a cable is accidentally cut or a connector is touched.

  * No 230V cables routed through the room — only to the power supply unit(s)
  * Non-technical staff (set designers, painters, decorators) can safely work around the wiring at all times
  * One type of industrial 24V power supply for the whole room — one or several units depending on power needs and cable lengths
  * I/O modules have built-in converters (24V→12V at 4A, 24V→5V at 4A), so connected devices can run at 5V, 12V, or 24V from a single supply

**230V devices** (such as high-power electromagnets or mains-powered equipment) can be controlled via external relays. However, any 230V wiring requires proper safety measures, and a **qualified electrician** must be involved during room construction.

===== Build Efficiency: CAN Bus =====

All I/O modules connect via a **single 4-wire CAN bus** cable (24V + GND + CAN_H + CAN_L).

  * **One cable** routes through the entire room instead of dozens of individual sensor wires
  * Fewer wall penetrations, less material, faster installation
  * I/O modules mount inside or next to props — short sensor cables, no long runs
  * CAN bus is an automotive/industrial standard — proven reliability, electromagnetic noise immunity
  * Adding a new module = connect 4 wires to the bus

===== Serviceability: One Device Type =====

Every room uses the same type of I/O module (currently [[products:er-01-rev-a|er-01-rev-a]]). Sensors are standard electronic components — reed switches, PIR sensors, buttons, Hall sensors — available from any electronics supplier.

  * **Spare parts inventory:** a few I/O modules + standard sensors
  * **Replacement time:** 2–5 minutes for a module, instant for a sensor
  * **Training:** 10 minutes — plug the cable, set the address with buttons
  * **No vendor lock-in on sensors:** a reed switch costs under 1 EUR from any source

===== Flexibility: Zero Field Logic in Practice =====

Because all game logic lives in Node-RED and no device in the room makes decisions, Wonder Controlz enables scenarios that are impossible or impractical with controller-based logic:

  * **Quick scenario swap** — switch the active flow in one click
  * **Language versions** — parameter in flow selects different media files per language
  * **Dynamic difficulty** — conditions based on time, progress, or player count
  * **Cross-puzzle communication** — any device can trigger any other device natively
  * **Multi-stage scenarios** — state machines, timers, conditions, loops
  * **A/B testing** — maintain two flow variants, toggle between them
  * **AI/LLM integration** — Node-RED HTTP request to any external API
  * **Seasonal modifications** — edit flow + swap media files, no physical changes needed

===== Remote Service =====

Every installation connects to the Wonder Controlz infrastructure via VPN.

  * **Remote diagnostics** — Node-RED logs, CAN bus states, system health
  * **Remote software updates** — push updates to any device in the field
  * **Remote scenario changes** — edit Node-RED flows without an on-site visit
  * **No internet required for operation** — VPN is for service only, the room runs fully offline