Own Technology
HStack
A KNX protocol stack we wrote ourselves, from the bit on the twisted pair up to the application layer.
System B
TP-1 twisted pair
KNX Data Secure
C source licence
Written in house, certified in its own right
Every layer of HStack is Horizentis code, from the 104 microsecond bit timing on the twisted pair up to the application layer. KNX Association certified it as a stack of its own, under manufacturer ID 867.
View Certificate
Certification
KNX Certificate of Conformity
KNX Association assessed HStack against the KNX Specifications and entered it in the register of qualified products on 1 September 2026. The certificate carries both the KNX and the KNX Secure trademark, and it stays valid for as long as the stack keeps meeting the rules it was tested against.
- Certificate number
- 867/23232/26
- Certified product
- HStack
- Specifications
- KNX v3.0.5
- Test report
- TRF-2026-03-4960324
Architecture
Every layer, all the way down
You write the application on top and adapt the porting layer at the bottom. Everything between them is HStack.
Your device application
Written by you, on the stack API
Licensed as C source
Application layer / AIL
Group objects, interface objects, function properties, KNX Data Secure
Transport layer
Multicast and connection oriented communication
Network layer
Individual and group addressing, hop count control
Data link layer
Framing, parity, acknowledge, repetition, collision
Physical layer
TP-1 bit timing in the microcontroller timers, 104 microsecond bit
Target porting layer
Flash, timer and RTOS hooks, adapt to your board
onsemi NCN5110 transceiver
Bit level line driver
KNX TP-1 bus
On the wire
The bottom layer, measured
A logic analyser on a live KNX line while HStack is running. Every burst is one telegram, read off the twisted pair and decoded field by field.
At a glance
What the stack is
Delivery
Licensed as source code, not as a black box
You receive the code, not a compiled library. The KNX layer of your product stays readable, debuggable and maintainable by your own team for the whole life of the product.
The whole stack in C
Every KNX layer from the physical layer to the application interface layer, with the headers that form the application API.
The porting layer
Timers, flash, reset and the programming button and LED for the STM32G0, ready to move onto your own board.
A project that builds
The Keil MDK project used for the certification build, an example application and an example ETS product database.
Working together
How a project runs
- 1
Hardware
Build your board around the STM32G0 and the NCN5110, or start from our reference design.
- 2
Port
Adapt the target layer to your board. Keep the reference pin assignment and there is nothing to change.
- 3
Declare
Describe your group objects, parameters and interface objects once, and build the matching ETS product database.
- 4
Apply
Write your application against the stack API. The stack calls you when a group object is updated, and you call it when a value changes.
- 5
Certify
The stack is already certified, so your device certification covers your application and your hardware, not the protocol implementation.
Documentation
Certificate, datasheet and conformance statement
All three documents are published in English. The signed PICS and PIXIT forms filed with KNX Association are supplied with the licence.
Certificate 867/23232/26 covers the HStack protocol stack. A device built on HStack still needs its own KNX product certification, which covers its application program, its hardware and its ETS product database.
Building a KNX device?
Tell us what you are building and we will tell you what porting it would take. Licence terms are quoted per project.