Hotel FCU programmes that still mix a retail-looking wall brick with a separate I/O board lose weeks in every guest-room RFQ. A hotel fan coil room controller Modbus puts the glass, sensors, and field outputs on one flush square - so Modbus RTU on RS-485 carries setpoints and status while valve and fan paths stay on the universal I/O you map in the ICD.
OEMHotelFCUModbusRoom ControllerWhite Label
Who specifies a hotel Fan Coil Room Controller
This article is for HVAC OEM product and R&D teams building hotel fan-coil platforms - not for installers shopping a webshop. If guest rooms need a branded wall controller with Modbus supervision and local I/O, this is the Room Controller path.
Alledio designs in Slovenia and manufactures in the EU for high-MOQ OEM programmes. The published commercial model starts at MOQ 1,000 (negotiable; 500 is possible when several Room Unit or Room Controller versions combined exceed 1,000). Samples ship with demo or test firmware under NDA via /oem.
Keep SKU families clean in the RFQ. A host-driven display without field I/O is the Room Unit. A 230 VAC relay brick for three-speed AC fans is the Thermostat. For a hotel fan coil that needs glass, sensors, and field I/O on one Modbus device, specify the hotel FCU Modbus Room Controller - not the 3-speed relay Thermostat, and not the host-driven Room Unit.
Typical hotel programmes care about consistent glass across floors, clear unoccupied modes, and a bus the PMS or BMS can already speak. Write that guest-room duty into the RFQ so purchasing does not substitute a retail thermostat by accident.
Hotel fan coil room controller Modbus - bus, I/O, and guest UI
On a hotel FCU the wall device must expose comfort setpoints, fan or Auto, and occupancy while the plant still owns safeties. On the Alledio Room Controller those live beside universal I/O - UI / UO / UIO classes you pin in the ICD before NRE starts.
Published maximum I/O mix is 2× UI, 3× UO, and 1× UIO. Concrete counts depend on the TH / TH1 / TH2 / TH3 version you order. Treat empty terminals as a commercial choice, not as free jumpers for the field team to invent later.
Modbus RTU on RS-485 is the default copper citizen (slave default; master on request), 9600-115200. Native BACnet and KNX are not published catalogue SKUs on this line - BACnet is available on request as a separate quote, not as a checkbox.
I/O map for hotel valves and fans
Analogue valve or EC fan commands sit in the UO class (0-10 V / 4-20 mA). Three-speed 230 VAC relays belong on the Thermostat family - keep that split when the RFQ mentions both hotel brand glass and mains fan stages.
Put termination, common reference, and cable class next to the pin list. Commissioning days disappear when the glass looks finished but the I/O class was never written down. Link the mechanical drawing to the same pack that lists Modbus registers.
Occupied, unoccupied, and interlocks
Hotel sequences usually need occupied / unoccupied setpoints, window or card contacts, and dew-point or drip-tray guards. The Room Controller can host application logic you specify while safeties stay on the board or BMS you already defend. Write which setpoints are only requests to the host.
Samples arrive with demo or test firmware so your lab can exercise valves, fan analogue or digital paths, Modbus, and the 3.5" panel before production NRE. Production firmware is quoted as NRE against your register map, branding pack, and I/O table.
Wiring a hotel fan coil room controller Modbus: terminal map
Hotel FCU teams lose the most time where the pin list meets the coil harness. Fix the terminal map early, and keep the labels identical across the ICD, the wiring diagram, and the commissioning sheet. The Room Controller numbering stays the same on every version, so a reduced-I/O SKU simply leaves some terminals unpopulated.
- Power: ±Vin on terminals 19 / 20 - 18-42 V DC (24 V recommended) or 24 VAC ±25%.
- Bus: Modbus A / B on terminals 9 / 10, RS-485 daisy chain with termination at both ends of the segment.
- Universal inputs: UI2 (3) and UI3 (5) - typical hotel use is a window or keycard contact and a pipe or changeover sensor.
- Universal outputs: UO2 (13), UO3 (15), UO4 (17) - for example 0-10 V valve, 0-10 V EC fan speed, and a fan-enable or second valve signal.
- Universal I/O: UIO1 (11) - often a drip-tray or dew-point alarm, or a spare output for a heater stage.
The full TH3 version carries all of these terminals. Smaller versions keep the same numbering, so drawings stay valid when purchasing moves between SKUs. Treat the mapping above as an example and confirm each assignment against the current datasheet before NRE starts.
Sequence of operation in a guest room
A clean hotel sequence reads in four steps. On check-in or keycard insert, the controller switches to occupied setpoints and lets the guest adjust within limits you define. While the window contact is open, valve and fan outputs go to a safe state. On checkout or after an unoccupied timeout, setpoints widen to save energy. Alarms such as drip tray, dew point, or a failed sensor raise a Modbus status bit so the BMS can flag the room.
Write which party owns each step. The wall device can run the local loop, but the BMS or PMS usually owns occupancy schedules and the alarm workflow.
Modbus register map essentials for hotel FCUs
A short, versioned register map saves more commissioning time than any feature. Group points so the BMS integrator reads the room in one block and writes commands in another.
- Setpoints and mode: occupied and unoccupied setpoints, setpoint limits, heat / cool / auto mode, fan Auto or manual stage.
- Commands and status: occupancy from the host, valve and fan output feedback, room temperature and humidity, optional CO2 or VOC.
- Alarms: window open, drip tray, dew point, sensor fault, and communication loss.
Addresses and scaling are fixed per project in the ICD, not invented on site. Samples with demo firmware let your lab test this map over RS-485 before the production firmware is quoted.
Hotel Room Controller vs relay thermostat and Room Unit
The Room Controller with Modbus RTU is built for low-voltage hotel FCU duty. If your coil still needs 230 VAC fan relays at the wall, see the relay thermostat guides instead: OEM Modbus relay thermostat, 3-speed FCU, or fan coil thermostat 3-speed AC fan Modbus. Those are mains-relay SKUs. Power on the Room Controller is 18-42 V DC (24 V recommended) or 24 VAC ±25% - never 230 VAC.
When the programme needs only a host-driven glass without field I/O, keep the RFQ on the Room Unit. When you need deeper sensing on a separate node, pair a Multi-Sensor. For the full I/O platform, read OEM room controller with universal I/O.
For coil topology, see the pipe guides - 4-pipe 0-10 V and 2-pipe 0-10 V valve - which cover valve matrices in detail. Here the focus is the guest-room Modbus setup.
Glass, mechanics, and OEM branding
A 3.5" 480×320 capacitive panel fits a 98 × 98 × 23 mm IP20 housing (150 g) - thicker than the 14 mm thermostat family so terminals and I/O fit. Capacitive glass keeps the controller in the same visual family as the Room Unit across hotel corridors.
OEM customisation covers logo, UI colours, widgets, hardware options, and firmware. You pay for the delta against a modular platform, not for reinventing a certified radio and a mould. The branding workflow itself is covered in our white-label Room Controller for HVAC guide. Same panel language appeared at MCE Milano 2026 and in how it feels.
When the RFQ also asks for flush depth, treat it as the same square family described in the 3.5 inch OEM HVAC touch panel thread - same glass language, different I/O and firmware load. That is how a controller line stays coherent next to a Room Unit SKU.
Product proof
Published proof for a hotel FCU Modbus programme is the combination of universal I/O, Modbus RTU, and OEM apps on one EU-made wall controller - not a consumer smart-home thermostat and not a 230 VAC relay thermostat.
| Topic | Published spec |
|---|---|
| Display | 3.5" LCD, 480 × 320, capacitive touch, auto brightness |
| Sensors (standard) | Temperature and humidity |
| Sensors (optional) | VOC, CO2 (400-5000 ppm), pressure, presence |
| Universal I/O (max) | 2× UI, 3× UO, 1× UIO (TH / TH1 / TH2 / TH3) |
| I/O classes | Analogue 0-10 V / 4-20 mA; digital open-collector / 0-30 V input |
| Fan path on RC | Analogue 0-10 V / EC on UO - not 3-speed 230 VAC relays |
| Bus | RS-485 Modbus RTU (slave default; master on request), 9600-115200 |
| Radio / API | Wi-Fi 2.4 GHz with OTA; MQTT/REST for authorised partners; BLE 5 ready |
| Power | 18-42 V DC (24 V recommended) or 24 VAC ±25%; never 230 VAC on RC |
| Mechanics | 98 × 98 × 23 mm, 150 g, IP20 |
| Origin | Designed Slovenia, manufactured EU |
| Commercial | OEM-only; MOQ 1,000 (negotiable; 500 if several RU/RC versions combined exceed 1,000); samples with demo/test firmware |
Not a catalogue claim here: native BACnet on standard Room Controller firmware; a KNX SKU; installer webshop pricing; 230 VAC relays. Confirm any cell on the current datasheet before you lock an RFQ. For deeper custom work use hardware and software development.
Compliance for connected variants starts from RED 2014/53/EU, RoHS, and the 10-year security-update window in the OEM agreement. Ask for the document pack before the first production lot. More on about.
FAQ
Is this a thermostat?
No. This is a Room Controller with universal I/O and Modbus RTU for hotel fan-coil programmes. The Thermostat family is the 230 VAC relay SKU.
Does hotel fan coil room controller Modbus apply to my FCU platform?
If you need branded guest-room glass plus Modbus supervision and versioned UI/UO/UIO, yes - lock the I/O version and register map in the ICD. If you only need 230 VAC three-speed relays, use the Thermostat path instead.
Can this configuration be driven over BACnet instead of Modbus RTU?
Modbus RTU on RS-485 ships as the default. Native BACnet is not a catalogue checkbox on this Room Controller line - budget a separate on-request quote if the RFQ demands it. KNX is not a published SKU.
What is the MOQ and can we get samples?
MOQ starts at 1,000 units and is negotiable. 500 is possible when several Room Unit or Room Controller versions combined exceed 1,000. Samples ship with demo or test firmware under NDA via the OEM conversation.
Where is the product made?
Designed in Slovenia and manufactured in the EU. Connected variants start from RED 2014/53/EU and RoHS; ask for the document pack before the first production lot.
Can an installer buy one from a webshop?
No. Alledio sells to OEMs. Installers and SIs get devices through the OEM channel.
What to do next
Start on the Alledio OEM Room Controller page, then open an OEM conversation for logo, UI, I/O version, firmware NRE, and samples. Bring the hotel pin map, Modbus register draft, power class, and MOQ. That is the shortest path from an RFQ sentence to a hotel fan coil Modbus wall controller under your brand.
