Larnitech CAN Bus: Planning Segments & Topology
Larnitech's DIN-rail modules communicate over one CAN data pair, not a wire per function. Before you pull cable, plan the trunk: where it starts, where it terminates, and how modules group by zone. This page covers the segment-planning principles that keep a Larnitech CAN installation reliable — honestly, without inventing power figures that belong on the datasheet.
How to plan a Larnitech CAN segment
Map the trunk as one line
Treat the CAN bus as a single linear run, not a star or ring. The Main Gateway provides two CAN connection points, one at each physical end of the trunk — that's where termination belongs.
Group modules by zone
Cluster relays, dimmers and input modules by floor or function so each branch off the trunk stays short and the panel layout stays legible.
Avoid long unterminated stubs
Long stub cables off the trunk risk signal reflection. Keep drops to nearby modules short, per standard CAN wiring practice.
Separate data from power, then check datasheets
Route the CAN twisted pair clear of 230V cabling. DIN modules draw their operating power from the panel's own supply rail — get exact current figures per module from Larnitech's datasheets before sizing that rail.
What disciplined segment planning gets you
termination points per segment
A Larnitech CAN trunk terminates only at its two physical ends, via the Main Gateway's two CAN ports — standard CAN bus practice, not a Larnitech-specific rule.
Linear, not star or ring
The trunk runs point to point; branch modules connect along it rather than radiating from a hub.
Termination discipline
Only the two physical ends of the bus carry termination — extra terminators or missing ones both cause problems.
Short, deliberate stubs
Where a module sits off the main run, keep the stub cable short instead of daisy-chaining long detours.
Zone-based grouping
Modules grouped by floor or function keep wiring diagrams and future troubleshooting straightforward.
Power checked per datasheet, not guessed
We don't publish invented current-draw or max-node numbers. We request them from Larnitech's module datasheets for your specific bill of materials.
What our panel-build support covers
Engineering input before the panel is wired, not after.
- CAN trunk and termination layout review
- Module grouping by zone or function
- Stub-length and cable-routing check
- Datasheet cross-check for module power draw
- IEC 61439 panel assembly
Frequently asked questions
Is Larnitech CAN bus the same as KNX?
No. Larnitech runs its own proprietary CAN-bus protocol, configured through its own app. KNX is the open ISO/IEC 14543-3 standard configured via ETS. Larnitech modules are not cross-certified with KNX devices.
What's the maximum number of nodes or bus length?
We don't publish a number here, because we haven't found one confirmed in Larnitech's public documentation. Check the current datasheet for your Main Gateway and modules, or ask your Larnitech supplier directly.
Do I need a termination resistor at every module?
No. Standard CAN topology terminates only at the two physical ends of the linear trunk — on a Larnitech installation, that's the Main Gateway's two CAN connection points.
Can modules run off a long stub cable from the trunk?
It's best avoided. Long unterminated stubs risk signal reflection on any CAN bus. Keep branch cables short and group nearby modules together instead.
Where do DIN modules get their operating power?
From the panel's own supply rail, separately from the CAN data pair. Exact current draw per module isn't something we invent — check the module's datasheet before finalizing your power budget.
Planning a Larnitech CAN panel?
Send us your module list and floor plan. We'll review trunk layout, termination and zone grouping before the panel goes to assembly.