Core philosophy

KNX is designed around intelligence at the edge. Each device — actuator, sensor, push-button — runs its own firmware and communicates directly with other devices via group address telegrams on the 2-wire TP bus. No controller is needed to keep the lights on. Removing or replacing a KNX router or programming PC has no effect on device operation.

Wirenboard is the opposite: intelligence is centralised in a DIN-rail Linux computer (WB-MAP or WB-7xx series) running Debian GNU/Linux. Field devices — relay boards, analogue I/O, 1-Wire temperature sensors — are dumb Modbus RTU slaves connected over RS-485. All automation logic runs as JavaScript rules (wb-rules engine) or Node-RED flows on the central controller. If the controller fails, all automation stops.

Hardware ecosystem

KNX field devices connect to a shared 2-wire bus. The ecosystem spans lighting actuators, blind actuators, fan-coil controllers, push-button interfaces, room thermostats, DALI gateways and energy meters from 500+ certified manufacturers. Device selection is competitive — any MDT, ABB, Gira, Theben, Jung, or Schneider device can replace any other without rewiring.

Wirenboard field devices are typically Wirenboard-branded DIN-rail Modbus RTU modules (WB-MR6C relay boards, WB-MAO analogue outputs, WB-MIO digital I/O, WB-MSW multi-sensor units) connected over RS-485 at 9,600 or 115,200 baud. Any third-party Modbus RTU device — industrial inverters, energy meters, HVAC controllers — can be added with a custom Modbus template.

Programming approach

KNX is programmed with ETS6. The engineer assigns group addresses to device communication objects — no programming language is required for standard switching, dimming and HVAC control. Complex logic (timer programs, multi-condition scenes, HVAC optimisation) requires an additional logic module (MDT SCN-Logic, Gira HomeServer) or a KNX IP controller.

Wirenboard logic is written as JavaScript in the wb-rules engine (a duktape-based JS interpreter) or built visually in Node-RED. Rules can subscribe to MQTT topics, write Modbus register values, set timers, and call external HTTP APIs. Grafana dashboards visualise historical data from the built-in InfluxDB. Any standard Linux tool — Python scripts, cron jobs, Mosquitto pub/sub — can be used alongside wb-rules.

// wb-rules: lower setpoint when room unoccupied for 15 min
defineRule("hvac_eco_mode", {
  whenChanged: "/devices/wb-msw-v3_22/controls/Motion",
  then: function(newValue, devName, cellName) {
    if (newValue == 0) {
      // No motion — start 15-min countdown
      startTimer("eco_timer", 15 * 60 * 1000, function() {
        dev["modbus_hvac/setpoint_temp"] = 18; // Eco setpoint
        log.info("HVAC: eco mode activated");
      });
    } else {
      // Motion detected — restore comfort setpoint
      stopTimer("eco_timer");
      dev["modbus_hvac/setpoint_temp"] = 22;
    }
  }
});

Protocol coverage

Use case fit by application type

Hybrid architecture: Wirenboard as BMS + KNX for room automation

The strongest real-world use of both systems is a hybrid: Wirenboard handles building services (HVAC Modbus, energy metering, solar inverter polling, alarm system I/O) while KNX manages room-level automation (lighting actuators, blind actuators, room thermostats, push-buttons, DALI). A KNX TCP/IP gateway bridges both layers — wb-rules can read and write KNX group addresses over KNXnet/IP.

Wirenboard WB-MAP (Debian Linux, central DIN-rail controller)
  │
  ├── RS-485 Modbus RTU backbone (9,600 baud)
  │     ├── WB-MAP12E — 12-channel energy sub-metering
  │     ├── Daikin VRV — Modbus adapter BRP069A61
  │     ├── SMA Sunny Boy — Modbus TCP solar inverter
  │     └── WB-MSW-V3 — CO2 / humidity / temperature sensor
  │
  ├── MQTT broker (Mosquitto) — internal message bus
  │     ├── Node-RED — visualisation and REST API flows
  │     └── Grafana + InfluxDB — energy dashboards
  │
  └── KNXnet/IP gateway (Weinzierl 730, UDP 47808)
        │  KNX TP bus (9,600 baud, 2-wire)
        ├── MDT AKU-1616 — 16-channel lighting actuator
        ├── MDT JAL-0800 — 8-channel blind actuator
        ├── MDT SCN-RTR — room thermostats (×8)
        └── Gira push-button interfaces

wb-rules KNX integration example:
  // Read KNX room temperature → publish to MQTT
  knxRead("1/0/1", function(value) {
    dev["knx_room1/temp"] = value; // → MQTT topic
  });
  // Write KNX setpoint when Modbus HVAC changes mode
  knxWrite("1/0/2", eco_active ? 18.0 : 22.0, "DPT_Value_Temp");