Need to connect KNX and Modbus? The Weble WBox routes KNX Modbus natively: one gateway speaks both protocols and maps data points in real time — no PC, no middleware, no cloud dependency.

KNX⇄WBoxgateway⇄ModbusOne WBox gateway · native conversion · no PC

The protocols

KNX

KNX is the worldwide standard for home and building control, running over twisted-pair, IP or RF.

KNX driver →

Modbus

Modbus (TCP/IP and RTU) connects PLCs, meters, variable-speed drives and countless industrial devices.

Modbus driver →

Typical use case

Room control is KNX, but the energy meters, variable-speed drives, heat pumps and inverters on site are Modbus (RTU or TCP) — two ecosystems that ignore each other. The WBox bridges them: live power, flow and pump status from Modbus equipment appear inside the KNX visualisation, and KNX switch or setpoint objects drive Modbus actuators. Facility teams get one consistent view and one set of controls instead of two parallel systems.

Example deployment

Typical scenario KNX building with a Modbus heat pump A KNX building installs a Modbus heat pump and a couple of Modbus energy meters. Rather than a separate tool for each, the WBox brings the heat pump's status, COP and power and the meter readings into the KNX visualisation, and lets KNX push a setpoint or an enable to the pump over Modbus. Technical documentation →

How the WBox bridges KNX and Modbus

Activate the KNX and Modbus drivers and map points in the editor. Modbus holding or input registers (e.g. active power in kW, a pump run state) map to KNX group addresses on DPT 14.x or 1.x; KNX commands map to Modbus coils or registers to start/stop a drive or push a setpoint. Word order, signed values and scaling are set per register, and a Blockly or JavaScript step can rescale or combine values on the way through — all on the gateway.

Example mapping

A worked example, all on one gateway:

  • Modbus holding 40001 active power → KNX 5/1/0 (DPT 14.056, W)
  • KNX 0/1/2 switch (DPT 1.001) → Modbus coil 00010
  • Modbus input 30002 pump running → KNX 5/0/1 (DPT 1.001)

Capacity & limits

  • KNX — KNX exposes the installation's group objects; a TP line carries up to 64 bus devices, extended through lines, areas and KNXnet/IP.
  • Modbus — Modbus addresses up to 247 slaves per line (RTU or TCP) — about 32 RTU devices per RS-485 segment before a repeater.

On the WBox, a driver licence enables the whole protocol — there is no artificial per-point tier to unlock. Capacity scales with the gateway model, from the compact S103 to the E413: you are bounded by the field bus, not by your licence.

Frequently asked questions

How do I connect KNX to Modbus equipment?

A WBox gateway with the KNX and Modbus drivers maps KNX group addresses to Modbus registers (RTU or TCP) and back, on one device — KNX rooms and Modbus meters, drives or heat pumps share a single view, with no PLC and no gateway PC.

Modbus RTU or Modbus TCP — which is supported?

Both: Modbus RTU over RS-485 and Modbus TCP/IP, as master or slave, on the same WBox as the KNX interface. Word order, signed values and scaling are set per register.

Is the KNX ⇄ Modbus bridge bidirectional?

Yes. A KNX command (DPT 1.x switch, DPT 9.x setpoint) can write a Modbus coil or register, and a Modbus value (active power, pump status) is exposed as a KNX group object — both directions.

Do I need a PLC between KNX and Modbus?

No. Both drivers are licence-activated on one WBox. For KNX TP choose the WBox S485 KNX, which has the twisted-pair interface on board; any model speaks Modbus over RS-485 or Ethernet.

What you need

One WBox gateway with these two driver licences:

KNX KNX Driver licence 100.00 CHF Modbus Modbus Driver licence 100.00 CHF

Route KNX Modbus on your project

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