KNX GRCS: what the manufacturer actually supplies
Three layers, three owners: PMS, GRMS and GRCS. We build the GRCS — the guest room control layer — and projects that know which layer they are buying run smoother.
Four room states, and what the controller must do in each
How the room layer hands data up
KNX is only the field bus. The controller exposes room status, energy counters and fault flags to the GRMS or BMS over the transport the building already runs: BACnet/IP or Modbus TCP through a KNX gateway, or HTTP/JSON for a cloud dashboard. That is why a KNX room can join a BACnet building without a second control system — the mapping happens at the gateway, not in the guest room. The data model is set out in our KNX to GRMS and PMS integration note.
Why owners separate the hardware decision from the software decision
Hotel software changes far more often than wiring does. When the controller is hardware with an open interface, a hotel can replace its PMS or its GRMS head end without touching a single room. When the two are sold as one closed stack, the rooms stay locked to the software vendor for the life of the building. We supply the hardware layer only: no PMS, no GRMS licence, no per-room subscription — which is why an integrator can place our controllers under any head end, including a competitor's.
What we can be held to as a manufacturer
Guest room control has been our single focus since 2013: 2,000+ projects, 130,000+ rooms on Hotekey Cloud, 40+ patents and software copyrights, national high-tech enterprise status, and CE / FCC / RoHS compliance, with assembly and testing run under an ISO 9001-managed process (SMT placed with audited EMS partners). KNX certification status differs by model, so we confirm the certified article number in writing at specification stage instead of claiming it on a web page. Fan coil control inside the GRMS is covered on the HT-FCU fan coil controller page.
What buyers ask a KNX GRCS manufacturer
Do you sell the GRMS software itself? No. We manufacture the room controller, panels, actuators and gateways, and expose them over KNX, BACnet/IP, Modbus TCP and an HTTP/JSON API. The GRMS head end is supplied by the integrator or by a software vendor of the owner's choice; ours only has to be readable by it.
Can your controllers sit under another vendor's GRMS? Yes, and they usually do. The room controller is a KNX device with a documented group-object list, so any KNX-capable head end can read it. What changes between head ends is the group-address mapping, which we hand over as a template.
Who commissions the KNX side? A KNX-certified integrator with ETS6. We supply the application program, the room template and remote support during the first room — we do not fly a technician out to press buttons for a whole tower.
