The Jablotron Futura L+ is a heat-recovery ventilation unit (MVHR) with an enthalpy counter-current exchanger, built by JABLOTRON LIVING TECHNOLOGY CZ for residential buildings. TapHome connects directly to the unit via Modbus TCP over Ethernet — no gateway or accessory module is required.
The template exposes ventilation mode selection, timed boost/circulation/overpressure functions, filter wear, supply/exhaust/outdoor temperature and humidity, heat-recovery and power metrics, feature enable switches (bypass, heating, cooling, anti-radon, auto-circulation), a temperature setpoint and read/write access to the 8 external-sensor and 8 external-button zones.
The Futura L+ has a condensed register address space that differs from the Futura L/M/S. A separate TapHome template (
Jablotron Futura L, M, S) exists for the older models. Importing the wrong template will produceILLEGAL_DATA_ADDRESSerrors or silently read junk. Verify the unit model before import.
Hardware connection
The Futura unit has a single RJ45 Ethernet connector on the main control board (X1 — LAN). Connect it to the same local network as TapHome Core using a standard Ethernet cable — no additional gateway, converter or accessory is required for TapHome integration.
Only the LAN connector (X1) is relevant for TapHome. The RS-485 buses (X2, X3) and AA bus (X6) are reserved for Jablotron’s own accessories (Alfa control panels, wall sensors, CoolBreeze, VarioBreeze) and are not exposed for external BMS use.
Control board connectors
| Connector | Type | Function |
|---|---|---|
| X1 | RJ45 | LAN — Modbus TCP to TapHome, MyJABLOTRON cloud |
| X2 | Phoenix Contact 3-pin | RS-485 bus — reserved / unused |
| X3 | Phoenix Contact 4-pin | RS-485 bus for Alfa panels, CO2 sensors, CoolBreeze |
| X4 | Phoenix Contact 2-pin | NTC 10 kΩ outdoor-temperature sensor |
| X5 | Phoenix Contact 5-pin | IN/OUT: LED, BST (boost), IN2, IN1 (0–10 V or contact), GND |
| X6 | Phoenix Contact 2-pin | AA bus (legacy single-panel bus) |
| T1 | PCB button | Short press = filter init, long press = Bluetooth service mode |
Analog inputs IN1/IN2 on X5 (0–10 V or potential-free contact) are an optional parallel BMS channel. Per the installation manual, analog control is superior to CO2 sensors (overrides them) — useful when Modbus TCP is not feasible, but TapHome integration uses only the LAN port.
Configuration
No activation, DIP switch or service menu is required to enable Modbus TCP on the Futura L+. The TCP server is active by default once the unit is powered and connected to the LAN.
When importing the template in TapHome, provide:
- IP Address — the unit’s IP on the local network
- Device address (Unit ID) — Modbus slave address (fixed value:
1)
Connection parameters:
| Parameter | Value |
|---|---|
| Protocol | Modbus TCP |
| Port | 502 |
| Device address | 1 |
| Available sockets | 1 (single concurrent client) |
| Firmware minimum | FLA.P.01.06 |
| Register range | IR:0–IR:26, HR:0–HR:273 |
The Futura L+ accepts only one Modbus TCP client at a time. If another system (Home Assistant, custom Modbus client, second TapHome Core) is already connected, TapHome will be unable to open the socket. Disconnect other Modbus TCP clients before importing the template. The MyJABLOTRON cloud link uses outbound HTTPS and does not occupy the Modbus socket.
Assign a static IP address to the Futura L+ in the router’s DHCP reservation table. The unit does not advertise itself via mDNS/Zeroconf, so a stable IP is required for reliable reconnection after power cycles.
Composite registers (uint32, int32) must be read and written in a single Modbus operation — partial reads return
ILLEGAL_DATA_ADDRESS. The TapHome template batches reads correctly; this error during normal operation typically indicates the wrong template variant (L/M/S vs L+) was imported.
Optional password protection
Holding register HR:920 (user_password) is 65535 = disabled by default, meaning Modbus writes are accepted without authentication. If an installer has enabled password protection via the MyJABLOTRON / MyCOMPANY app, Modbus writes will silently fail until the access code is written to HR:900 within the password timeout (default 300 s, HR:922). For typical TapHome installations, leave the password disabled.
Device capabilities
The template exposes 84 devices covering unit-wide metrics, timed functions, feature toggles, the temperature setpoint and the 8 external-sensor and 8 external-button zones.
Ventilation mode
- Ventilation Mode — selector for fan power via holding register HR:0. Exposed values: Off (0), manual Level 1–5 (1–5), Automatic (6). The template additionally exposes numeric values 7–9 that have no documented meaning in the register map and should be treated as reserved.
Timed functions
Three timed functions are exposed as multi-value switches with 10 preset durations (Off, 30 s, 60 s, 5 min, 10 min, 15 min, 30 min, 1 h, 1.5 h, 2 h). Each function also exposes a Remaining Time [s] service attribute and a service action accepting a custom countdown value (1–7200 s):
- Boost Function (HR:1) — maximum ventilation for the selected period
- Circulation Function (HR:2) — air recirculation (internal loop) without heat recovery
- Overpressure Function (HR:3) — supply > exhaust, useful during fireplace ignition
Reading the register returns the remaining countdown in seconds; writing arms the function.
Air path sensors
Three of the unit’s air-path sensor positions are exposed, each combining temperature and humidity from separate input registers:
| Device | Temperature | Humidity | Description |
|---|---|---|---|
| Outdoor Air | IR:12 | IR:16 | Ambient air before heat recovery |
| Supply Air | IR:13 | IR:17 | Fresh air delivered into the building |
| Exhaust Air | IR:15 | IR:19 | Waste air leaving the building |
| External NTC Sensor | IR:20 | — | Optional NTC 10 kΩ outdoor probe on X4 |
Temperatures are stored as 0.1 °C (int16) and scaled to °C in the template; humidity values are scaled to fractions (0–1) from the raw 0.1 % reading.
The External NTC Sensor reports
-99when no probe is connected to the X4 connector. The template maps this sentinel to NaN so the value does not appear as a valid temperature in TapHome.
Performance monitoring
- Heat Recovery (IR:23) — instantaneous heat recovered from exhaust into supply, in W
- Power Consumption (IR:22) — total electrical power draw of the unit, in W
- Heating Power (IR:24) — current draw of the internal 350 W electric post-heater, in W
- Air Flow (IR:25) — combined supply + exhaust volumetric flow, in m³/h
- Filter Wear Level (IR:21) — filter contamination level: 0 % = clean, 100 % = replacement needed. Exposed as a dimmer-style level (0.0–1.0).
Temperature setpoint
- Preferred Temperature (HR:4) — indoor temperature setpoint for the unit’s internal control loop, in °C. Reads and writes are scaled ×10 (0.1 °C resolution).
Feature enable switches
Binary on/off switches controlling unit behavior:
- Bypass Enable (HR:7) — automatic bypass of the heat exchanger when free cooling is useful
- Cooling Enable (HR:9) — enables the CoolBreeze cooling module (requires accessory)
- Heating Enable (HR:15) — enables the internal 350 W electric post-heater
- Anti-Radon Protection Enable (HR:6) — reduced recirculation to prevent radon accumulation
- Auto Circulation (HR:10) — automatic air-recirculation function
- Time Program (HR:5) — weekly time-program scheduling
External zone sensors (zones 1–8)
The Futura L+ accepts values of up to 8 external CO2/temperature/humidity sensors, one per zone. These are inputs of the Futura: TapHome writes the values into them, it does not read Jablotron sensors from them (see Using TapHome sensors for zone ventilation below). For each of the 8 zones the template exposes:
- Sensor Present — enables the sensor input for the zone
- Temperature — external temperature value (−20 °C to 100 °C, 0.1 °C resolution)
- Humidity — relative humidity (0–100 %)
- CO2 — CO2 level (0–10 000 ppm)
Zone sensor holding-register blocks are at HR:100–175 (10 registers per zone, stride 10).
The measured CO2, temperature and humidity of zones 1–8 (IR:100–173) are available in the L+ Modbus map but not in the template. They can be added as Modbus variables.
External zone buttons (zones 1–8)
The Futura L+ also supports 8 external wall buttons for quick boost or kitchen-hood activation. Per zone:
- Button Present — enables the button input
- Button Mode — selects between Boost (0) and Kitchen Hood / Digestoř (1)
- Button Timer — countdown (0–10 800 s)
- Button Activation — triggers the button action (3-hour time limit)
Zone button holding-register blocks are at HR:200–273 (10 registers per zone, stride 10).
Module service attributes
Two diagnostic attributes are exposed at module level:
- MAC Address (IR:2–IR:4) — the unit’s Ethernet MAC, assembled from three 16-bit registers and formatted as a hex string
- Firmware Version (IR:0) — the L+ firmware revision (
uint32)
Using TapHome sensors for zone ventilation
With VarioBreeze room-by-room ventilation, the Futura pairs the components of a zone by the same DIP switch setting (zone 1–8). Over Modbus it also provides an external sensor input for each of the 8 zones, so TapHome sensors — for example a wall switch with a built-in CO2 sensor — can supply the zone values. The direction is TapHome → Futura.
For each room:
- Zone number — the DIP switch setting on the valve of that room (1–8). Use the zone devices with the same number.
- Turn on Zone N – Sensor Present (in the app: Zona N - Přítomnost externích čidel).
- Add a Smart Rule Formula for each zone value:
- Zone N – CO2 (Zona N - CO2) = room CO2 sensor, in ppm
- Zone N – Temperature (Zona N - Teplota) = room temperature, in °C
- Zone N – Humidity (Zona N - vlhkost) = room humidity × 100
- Set Ventilation Mode (Výkon větrání) to Automatic — levels 1–5 are manual fan levels.
TapHome stores humidity as a fraction (0–1), the Futura expects percent (0–100). Without × 100 in the formula, a humidity of 0.45 is written as 0 %.
Fill all three values of every zone with Sensor Present turned on. A zone device without a rule keeps the value 0 and TapHome writes it to the Futura — the zone then reports 0 °C and 0 %.
Troubleshooting
Zone sensor values are 0
TapHome writes the current value of each zone device to the Futura on every poll. A zone device without a Smart Rule keeps the value 0, so the Futura receives 0 ppm, 0 °C or 0 %. Add a rule for every value of an active zone and keep Sensor Present off for zones that are not used. If only the humidity is 0, the formula is missing the × 100.
The Futura does not react to zone sensors
- Ventilation Mode is set to Automatic — levels 1–5 are manual
- Zone N – Sensor Present is turned on for that zone
- The zone number used in TapHome matches the DIP switch setting on the zone’s valve
No Modbus communication
- Verify the Ethernet cable is connected to X1 (LAN) on the main board — not to any Phoenix Contact terminal
- Confirm the unit’s IP address via the router’s DHCP lease table or the MyJABLOTRON app; ensure TapHome Core and the Futura are on the same subnet
- Check that no firewall is blocking TCP port 502 between TapHome and the unit
- Ensure no other Modbus TCP client (Home Assistant, diagnostic tool, second TapHome Core) is holding the single available socket — disconnect any such client and retry
- Verify firmware is FLA.P.01.06 or newer (visible in MyJABLOTRON)
ILLEGAL_DATA_ADDRESS errors
Composite registers (uint32 bitmaps, int32 timestamps) must be read in a single Modbus operation. In practice this error during normal TapHome polling indicates the wrong template variant was imported. The L/M/S template addresses registers at IR:30–52 / HR:0–17 which do not exist in the L+ map (L+ starts at IR:0 and HR:0 with a condensed layout). Re-import the correct Jablotron Futura L+ template.
Modbus writes have no effect
If the unit responds to reads but ignores writes (mode changes, timer starts, enable toggles), the installer may have enabled the user password in MyJABLOTRON. Either disable the password (write 65535 to HR:920 while logged in) or keep HR:900 authenticated by writing the access code within the HR:922 timeout window. For typical TapHome installations the password should remain disabled.
Mode or timer values look wrong
The Futura L+ uses 0.1 °C and 0.1 % encoding for temperatures and humidity. The TapHome template already applies the correct scaling (÷10 for temperature, ÷1000 for humidity in the supply/exhaust/outdoor devices). If values appear 10× or 1000× off, the wrong template (L/M/S) was imported — the scaling factors differ between variants.
