Centralised AC control
TCMsys™
Centralised monitoring and control of every air-conditioning unit on a site. TCMsys cuts consumption through occupancy-driven setback, raises alarms the moment something is wrong, and flags a failing unit before your guest does.
- Up to 2,048 rooms per site
- 8 AC brands, mixed freely
- AC and non-AC rooms
- Modbus, REST & PMS integration
The room device
It starts with the TCM Module
One module per room, between the air-conditioning unit and the guest. It drives the unit directly across eight manufacturers, carries the keycard, door, do-not-disturb, make-my-room and laundry inputs, reports live room temperature and setpoint, and has the room at temperature before the guest reaches the door. Everything above it on this page exists to aggregate what this device already does on its own.
TCM Module in detail- Direct AC control, 8 brands
- Keycard occupancy
- Do Not Disturb
- Make My Room
- Pick My Laundry
- Live temperature & setpoint
- Pre-arrival comfort
- Autonomous when the network drops
How it is built
Three layers, each able to stand alone
Intelligence sits as close to the room as possible. Every layer holds enough state to keep working when the layer above it goes quiet — which is what separates a control system from a monitoring dashboard.
TCM Module
One per room or zone
An embedded controller that sits between the air-conditioning unit and the room. It drives the unit directly, reads the guest inputs — keycard, door, do-not-disturb, make-up-room, laundry — and keeps running on its own if it loses contact with the site.
Sub-Gateway
One per bus segment
A segment controller managing up to 64 room modules over the TCMbus. It polls continuously, caches the state of its rooms and relays events upward, so the site platform is never the bottleneck.
Coordinator
One per site
The software platform. It aggregates every segment into a single picture of the building and provides the dashboard, REST API, reporting, alerting and the integration surface for property and building management systems.
Why it matters: a room module that has lost the network still holds its setpoint, still honours the keycard and still logs what happened. When the link returns, the site catches up — it does not start from nothing.
Room options
Every room on the system, whether or not it has air conditioning
Buildings are not uniform. Some rooms have a modern unit with a digital interface, some have an older one, and some have none at all. All three get the same module, the same bus and the same place on the dashboard.
AC rooms
Full comfort controlThe room module connects directly to the air-conditioning unit over MBus or RS-485 and takes command of it: power, mode, setpoint, fan and vanes, plus full read-back of the unit’s own state and fault codes. Occupancy setback, pre-arrival cooling and door-alarm policy all act on the unit itself.
- Eight AC manufacturers supported natively
- Mixed brands allowed on the same bus segment
- Setback and failsafe stored on the module, not the server
- Guest remote keeps working, inside the limits you set
Non-AC rooms
Monitoring & guest signalsRooms with no air conditioning, with a unit that has no digital interface, or that you simply do not want under automatic control still get a module. It carries the same guest inputs, the same alarms and the same reporting — so back-of-house rooms, older wings, corridors and common areas appear on the dashboard alongside everything else.
- Keycard occupancy, door state, DND, make-my-room, laundry, auxiliary input
- Door-open, stuck-input and offline alarms
- Occupancy history and housekeeping signals for the whole estate
- Upgrade path: populate the AC port later without re-cabling the room
One module handles one air-conditioning unit over one interface — the standard hotel installation. The interface is set by which connector is populated at build time, so you order the variant each room actually needs instead of paying for hardware that will never be wired.
AC compatibility
Eight manufacturers, mixed freely on the same bus
Hotel wings get refurbished at different times, and the plant reflects it. TCMsys does not require you to standardise the estate before you can control it — modules on the same segment can be talking to entirely different brands.
Mitsubishi Electric
- Notes
- Full feature set, over the unit’s own service port — no third-party gateway needed.
Daikin
- Notes
- S21 / D-BUS. Covers residential and light-commercial units.
LG
- Notes
- LGAP / PI-485 gateway protocol, including VRF systems.
Samsung
- Notes
- NASA protocol for DVM systems.
Panasonic
- Notes
- CS-CZ / CZ-CFUNC2. Adapter module required on some models.
Hitachi
- Notes
- H-LINK and H-LINK II for newer VRF models.
Toshiba
- Notes
- AB protocol.
Carrier / Trane
- Notes
- BACnet MS/TP. Available as a firmware extension on request.
Each brand is handled by a dedicated driver in the room-module firmware. Units outside this list can usually be added — send us the model and the protocol documentation.
What the system sets
- Power on / off
- Mode — cool, heat, dry, fan, auto
- Setpoint temperature
- Fan speed
- Vertical vane position
- Horizontal / wide vane position
- External room temperature override
What the system reads back
- Power state and current mode
- Active setpoint
- Measured room temperature
- Fan speed and vane positions
- Filter status
- Manufacturer error and fault codes
Floor-wide control
One command sets the same state on every room of a floor — for an evacuation, an end-of-season shutdown or a full-floor checkout.
Arbitrary groups
VIP floors, smoking floors, meeting rooms — define any set of rooms and command them together.
External temperature
Where the unit allows it, push a corrected room temperature to override a badly placed internal sensor.
TCMbus
The bus is the product
Most of what makes a building-scale control system reliable happens below the dashboard. TCMbus is our own wired protocol between the room modules, the segment gateways and the coordinator — designed for buildings, not for benches.
Deterministic, collision-free
The upward bus runs event-driven TDMA: the coordinator broadcasts a sync every 50 ms and each gateway answers only in its own 1 ms slot, and only when it has something to say. No contention, no retry storms, and a bus that is silent when the building is quiet.
Parallel segments
All 32 segments are polled at once by their own gateways rather than in sequence from the centre. A full 64-room segment completes its cycle in well under half a second, and adding segments does not slow the others down.
Runs on structured cable
Room segments use ordinary Cat6 in a daisy-chain from module to module — up to 600 m per segment. Your electrical contractor already knows how to install it, and the line rate leaves a wide margin at full distance.
Self-healing addresses
If a module loses its bus address, the gateway discovers it, matches it against the commissioned room list by factory serial number, and reassigns the correct address on its own. No service call, no guesswork.
Commission from the centre
Discovery, address assignment and configuration for any module on any segment are relayed from the coordinator. An engineer never has to open 32 riser cupboards to commission a building.
Firmware over the live bus
Updates stage to on-board memory while the room carries on being controlled, then apply at the next reboot with a checksum gate. A failed transfer leaves the module on the firmware it already had — a guest room is not a place to brick a device.
Buffered through outages
A gateway that loses the coordinator keeps polling, keeps enforcing policy and keeps recording. Room state changes queue in a ring buffer and replay in order once the link is back.
Instrumented end to end
Per-device fault codes, per-segment bus utilisation, live online/offline state and activity indication at every module. When something is wrong the engineer can see where, not just that.
Measured, not estimated
Every timing figure below is derived from the physical bus budget and verified against it, at the full 64-device segment load. They are requirements the system is tested to — not best-case marketing numbers.
- Event to coordinator
- Under 1 s
- Command acknowledged
- ~104 ms typical
- Offline device detected
- Within 5 s
- Segment polling cycle
- 500 ms, 64 rooms
- Dashboard update
- Under 1 s, pushed
- Full state rebuild
- Under 10 s, all 2,048 rooms
Capabilities
What the system does
Occupancy-based setback
An empty room does not need to be cooled to the same setpoint as an occupied one. Setback engages on keycard and door state, and releases the moment the guest returns.
Mixed-brand support
Estates rarely have one brand of air conditioner throughout. Eight manufacturers are supported natively, and brands can be mixed freely on the same bus segment.
Pre-arrival comfort
Reservation data from the property management system brings the room to its comfort setpoint before the guest reaches the door. Arrival temperature stops being a matter of luck.
Guest input handling
Do-not-disturb, make-up-room and laundry requests are first-class signals, not afterthoughts. Housekeeping sees them the moment a guest presses the button.
Door and tamper alarms
A door left open with the unit running is both a comfort problem and an energy problem. The system flags it immediately and applies whichever AC policy you have chosen.
Predictive maintenance
Operational trends surface a unit that is drifting before it fails, and every alert opens a trackable work order. Maintenance gets scheduled instead of dispatched at midnight.
Keeps working when the network does not
If the site platform becomes unreachable, room modules fall back to autonomous behaviour and keep the guest comfortable. Nothing depends on a cloud round-trip to work.
Energy reporting
Runtime per room per day, estimated setback savings in kWh, and occupancy measured against actual AC usage. The numbers an energy manager needs to defend the investment.
Remote firmware updates
Room modules and gateways update over the live bus. A firmware fix does not mean unlocking two thousand guest rooms one at a time.
Energy
Setback that matches your property, not a default
A budget property wants the unit off. A luxury property would rather hold a comfortable setpoint than risk a guest walking into a hot room. Both are correct, so both are configurable — per room or per floor.
Off after delay
The unit shuts down a configurable number of minutes after the room goes vacant. The strategy for budget and mid-market properties.
Setback setpoint
The unit drops to a holding setpoint instead of stopping, so the room is never far from comfortable. The strategy for luxury properties.
Combined
Hold the setback setpoint for a period, then shut down. Both savings and a recoverable room.
Savings do not depend on the server. Setback policy is stored on the room module itself and executes even with the coordinator offline. The energy case survives a network outage, a server restart and a power cut.
Signals
What each room reports
Six opto-isolated inputs per module, assigned to a function at commissioning rather than hardwired at the factory — so an unusual installation does not need an unusual part.
Keycard
- What it drives
- Room occupied / vacant — drives setback and the housekeeping cycle.
Door sensor
- What it drives
- Opto-isolated 230 V AC detect. Feeds the door-open alarm and security logic.
Do Not Disturb
- What it drives
- Visible to housekeeping the instant the guest presses it.
Make My Room
- What it drives
- Raises a cleaning request against the room, with timestamp.
Laundry
- What it drives
- Pickup request routed to the housekeeping queue.
Auxiliary
- What it drives
- Spare opto-isolated channel — configurable polarity, assigned at commissioning.
Alarms raised
- Door open
- Device offline
- AC unit fault
- AC interface timeout
- AC interface error
- Temperature sensor fault
- Input stuck active
- Bus collision
Routing is configurable per alarm type and per recipient — front desk, housekeeping, engineering, security — and changes without touching code. Manufacturer fault codes are translated into plain descriptions rather than shown as raw hex.
Watched continuously
- Filter dirty — reported by the unit, or inferred from runtime
- Communication timeout on the AC interface
- Room not reaching setpoint — deviation beyond threshold, sustained
- Unit running continuously while the room is unoccupied
- Repeated AC error codes within a rolling window
- Door open with the unit running beyond threshold
Every threshold is configurable per room or globally, because a fixed threshold that works in one climate generates noise in another.
Integration
Four ways into the system
The coordinator is designed to be integrated with, not worked around. Whichever head-end your estate already runs, there is a documented route in.
REST API
PrimaryEvery room state, event, alarm and configuration object is reachable over a versioned REST API with generated OpenAPI documentation. Breaking changes bump the major version and the previous major stays available, so a third-party adapter is never forced to migrate on our schedule.
WebSocket push
RealtimeState changes are pushed, not polled. A subscribed BMS or dashboard sees a change within a second of the physical event, and dashboard clients never poll the server.
Modbus server endpoints
BMS / SCADAFor estates standardised on Modbus, the coordinator exposes server-side endpoints so an existing BMS or SCADA head-end can poll room and plant state directly from its native register map — no bespoke adapter, no middleware box in the riser.
PMS events
HospitalityCheck-in, check-out and reservation events arrive by REST or webhook, and the PMS stays the authority on occupancy. Opera / Fidelio, Protel and any system that can deliver a webhook are supported. If the PMS link drops, the system falls back to keycard occupancy — AC control never depends on it.
Full detail on payloads, authentication and event catalogues is on the integrations page.
Access
Everyone sees their own job
The front desk should not be reading engineering logs, and an installer should not keep access after the building is handed over. Roles are enforced on every endpoint, not just hidden in the interface.
Front desk
- What they get
- Room status, DND and make-up-room signals, manual AC override, alarm acknowledgement.
Housekeeping supervisor
- What they get
- Room-ready status, laundry requests, make-up-room alerts, DND state.
Engineering & maintenance
- What they get
- Device alarms, offline list, work orders, AC fault history, diagnostic logs — no guest data.
GM & energy manager
- What they get
- Energy reports, setback policy, site-wide scheduling, alert thresholds.
Installer
- What they get
- Commissioning tools only, on a time-limited account that expires by itself.
Super admin
- What they get
- System configuration, users, firmware scheduling, audit log, data retention.
Administrative actions — user changes, configuration edits, firmware triggers, alarm acknowledgements, data purges — are written to an audit log that no role can edit, including the super admin.
Where it fits
Two markets, one platform
Hotels
Room AC control tied to occupancy and the housekeeping cycle. Guest comfort on arrival, setback on departure, door alarms, and maintenance alerting across the whole property.
Commercial offices
Zone-level control with occupancy-based setback outside working hours, energy reporting by floor or tenant, and the same maintenance alerting.
Room module
- Operating temperature
- 0 °C to +50 °C
- Storage temperature
- −20 °C to +70 °C
- Humidity
- 10–90 % RH, non-condensing
- Ingress protection
- IP20, indoor
- Supply
- 85–265 V AC, 50/60 Hz
- Power draw
- Under 3 W
- Protection
- Fuse, surge and TVS clamping
- Guest inputs
- Opto-isolated, 5 kV rms
At a glance
System scale
- Rooms per site
- 2,048
- Bus segments per site
- 32
- Rooms per segment
- 64
- Segment cable run
- Up to 600 m
- Room wiring
- Cat6 daisy-chain
- Room bus
- TCMbus over RS-485
- Deployment
- On-prem, cloud or hybrid
Larger estates are handled by federating multiple sites. Talk to us about anything beyond a single-site limit.
Graceful degradation
Losing one gateway affects only the rooms on that segment; every other segment carries on. Losing the coordinator does not stop room-level control or setback at all. The dashboard reports how much capacity you have left — rooms, gateways, bus headroom, storage — and warns before an expansion runs out of room rather than after.
Find out what TCMsys would save you
Send us your room count, the AC brands installed and your current setpoint policy. We will come back with a realistic view of the energy savings and what the installation involves.