Casambi BLE Mesh Lighting and KNX: A Practical Integration Guide
Casambi is a Bluetooth 5.0 mesh lighting system that removes the DALI-2 or 0-10V control cable between fixtures, commissioned entirely through its mobile app. Bridging that mesh into a KNX installation means adding a Casambi Gateway (CGW) unit and mapping its Modbus TCP or REST interface into KNX group addresses — not installing a native KNX product.
What Casambi Actually Is
Casambi is a Bluetooth 5.0 mesh control layer for lighting, not a wired bus: instead of running DALI-2 or 0-10V control cable back to a panel, each luminaire either ships “Casambi-ready” with the radio and firmware built into the driver, or gets a small Casambi Bluetooth Unit (CBU) wired between a standard 0-10V or DALI-2 driver and mains. Every unit both receives and relays commands, so the mesh self-heals if one fixture is switched off for maintenance.
Commissioning happens entirely in the Casambi app over Bluetooth — pair, group, build scenes — with no central controller needed for a stand-alone room. That is the appeal for retrofit work: no new cable route, no bus wiring device at every luminaire, no DALI-2 commissioning tool on site. The trade-off is that Casambi is not a KNX product line; every integration runs through a gateway that translates the mesh into something a KNX installation can address.
When Casambi Replaces DALI-2 Wiring — And When It Doesn't
Casambi earns its keep where pulling new control cable is the expensive part of the job: listed buildings, occupied retrofits, suspended-ceiling replacements, or any site where mains wiring already exists but a DALI-2 bus does not. Since each CBU or Casambi-ready driver only needs a 230 V mains connection, adding lighting control after the fact skips the second cable run entirely.
It does not replace DALI-2 on large open floors or where individual short-address diagnostics matter. Casambi's own commissioning guidance keeps a single network small enough that relay hops stay short and reaction time stays fast — in practice that means splitting a large open-plan floor into several Casambi networks bridged separately, not scaling one flat mesh across the whole building.
Metal panel enclosures attenuate BLE 5.0. A CBU or Casambi-ready driver mounted inside a closed metal luminaire housing or behind a large distribution board can drop out of mesh range just a few metres from its neighbours. Plan node density and enclosure material before finalising the fixture schedule, not after.
How the CGW Gateway Bridges Casambi into KNX
The Casambi Gateway (CGW) is the wired unit that sits on the local network and exposes the mesh's state — luminaire and group on/off, dim level, and colour temperature on tunable-white fixtures — over a local REST API and a Modbus TCP register set. KNX has no native Casambi driver, so a second device (a Modbus TCP-to-KNX gateway, or a KNX logic controller with a Modbus TCP client) reads the CGW's registers and writes them to KNX group addresses, and vice versa for commands going the other way.
Before wiring anything, pull the current Casambi Gateway integration manual and confirm the register map for the firmware version installed on site — Casambi has changed the register layout between major CGW firmware releases, and the manual is the only place the addresses are guaranteed current.
| Casambi Gateway function | Typical KNX datapoint type | Notes |
|---|---|---|
| Luminaire/group switch | DPT 1.001 (Switch) | One KNX group address per Casambi group, not per DALI-2 short address |
| Dim level 0-100% | DPT 5.001 (Scaling) | Confirm the CGW register scale before mapping — firmware versions differ on 0-254 vs 0-100 |
| Colour temperature (tunable white) | DPT 7.600 (Colour Temperature) | Only present on fixtures actually running tunable-white Casambi firmware |
| Scene recall | DPT 18.001 (Scene Control) | Trigger only — the scene content itself still lives in the Casambi app, not in KNX |
Commissioning Procedure, Step by Step
Commission the Casambi side completely before touching KNX — a mesh that isn't stable on its own will never look stable through a gateway.
- Pair every CBU or Casambi-ready driver in the app and confirm signal strength at each fixture
- Group luminaires and build the scenes the KNX side will trigger
- Leave the network running unattended for at least 24 hours and check for dropped nodes
- Add the CGW to the network with a static IP or a DHCP reservation
- Point the Modbus TCP/REST bridge device at that IP and import the current register map
- Map each register to a KNX group address, then test switch, dim and scene recall independently
Failure Modes Installers Actually Hit
Latency is the first thing clients notice: a command relayed across several BLE hops before it reaches the far end of a mesh can take noticeably longer than a wired DALI-2 bus, especially right after a fixture has been powered back up and is still rejoining. Do not promise show-lighting-grade synchronisation across a large mesh.
Firmware version dependency is the gotcha that shows up months after handover: an automatic Casambi app or CGW firmware update can change the Modbus register layout, silently breaking the KNX mapping until someone re-reads the current integration manual and re-maps the affected registers.
Two more to plan for: DALI-2 short-address diagnostics do not survive the trip through Casambi and the CGW — only group-level state reaches KNX, so a technician still needs the Casambi app for individual driver fault-finding. And a shared 24 V DC PSU feeding several CBUs needs sizing from each unit's actual datasheet current draw, not a round number, with headroom for mesh-relay and firmware-update current spikes.
Where This Sits in the Panel Build
A CGW and its Modbus/KNX bridge are low-voltage, low-current devices that belong on their own DIN rail run inside the distribution board, next to — not sharing a terminal block with — the KNX line's bus power supply. PanelCraft's panel-build service allocates that DIN rail space and the 24 V DC bus during the initial layout, so the gateway hardware has a documented, labelled home before commissioning day instead of being added as an afterthought. See the wiring fundamentals in the knowledge base before laying out a mixed Casambi/KNX panel.
Frequently Asked Questions
Does Casambi need a central hub to work?
No. A stand-alone Casambi network runs peer-to-peer over Bluetooth mesh, commissioned from the app; a CGW unit is only needed when you want to bridge that network into KNX, Modbus, or another building system.
Can Casambi control a DALI-2 driver's dimming curve directly?
Yes, through a CBU wired to the DALI-2 driver — the CBU handles the DALI-2 addressing internally, but that per-driver detail is not exposed over the CGW's KNX-facing registers, only group-level state is.
What's the difference between a Casambi-ready driver and a CBU module?
A Casambi-ready driver has the Bluetooth radio and firmware built in from the factory; a CBU is a separate add-on unit wired between mains, a standard 0-10V or DALI-2 driver, and the fixture, used when the driver itself is not Casambi-ready.
How many luminaires can one Casambi network reliably handle?
Casambi's own guidance keeps a single network in the range where relay hops stay short and commands stay responsive — for larger open-plan floors, split the space into several networks bridged separately rather than scaling one flat mesh.
Does the CGW gateway need an internet connection to bridge into KNX?
No. Once the mesh is commissioned, the CGW's local Modbus TCP and REST interfaces work on the LAN without internet access; cloud connectivity is only needed for remote app access or firmware updates.
Can a KNX pushbutton trigger a Casambi scene?
Yes, if the scene-recall register is mapped to a KNX group address (DPT 18.001) through the CGW bridge — the pushbutton sends a KNX telegram, the bridge writes it to the CGW, and the CGW replays the scene stored in the Casambi app.
Speccing a Panel Around a Casambi/KNX Bridge?
PanelCraft designs and CE-certifies the distribution board around the CGW, its Modbus/KNX bridge and the 24 V DC bus it needs — wired, labelled and ready for commissioning.
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