--- title: "Zehnder ComfoConnect PRO" description: "Zehnder ComfoConnect PRO Modbus TCP gateway connected to TapHome for controlling Zehnder ComfoAir ventilation systems." url: "https://taphome.com/en/compatibility/zehnder-comfoconnect-pro/" language: en lastmod: 2026-03-21 generator: hugo ai: topics: ["modbus-tcp","air-recovery","heat-recovery-ventilation","ethernet","gateway"] questions: ["How to integrate Zehnder ComfoAir ventilation with TapHome?","What does the Zehnder ComfoConnect PRO TapHome template measure and control?","How to connect Zehnder ComfoConnect PRO via Modbus TCP to TapHome?","How to enable Modbus TCP on the Zehnder ComfoConnect PRO?","What ventilation presets are available for Zehnder ComfoAir in TapHome?","How to activate boost mode on Zehnder ComfoAir via TapHome?","Does the ComfoConnect PRO work with ComfoAir Classic or Standard 300 units?"] --- # Zehnder ComfoConnect PRO Communication: Modbus TCP - [Zehnder ComfoConnect PRO Product Page](https://www.zehnder.com/) The Zehnder ComfoConnect PRO is a modular gateway that bridges Zehnder ComfoAir ventilation units (Q350, Q450, Q600 and Flex) to external building automation systems via Modbus TCP. TapHome connects to the gateway over Ethernet — the gateway then communicates with the ventilation unit over the ComfoNet CAN bus. The template provides ventilation preset control (Away / Low / Medium / High), four temperature and humidity sensors (extract, exhaust, outdoor, supply), supply airflow reading, filter status monitoring, temperature profile selection and a configurable boost mode. ## Hardware connection The ComfoConnect PRO sits between the home network and the Zehnder ventilation unit. It connects to the ventilation unit via the included ComfoNet cable (CAN bus) and to the network via Ethernet (RJ45) or Wi-Fi. ![Zehnder ComfoConnect PRO system diagram — network, gateway and ventilation unit](https://taphome.com/images/compatibility/zehnder-comfoconnect-pro/system-diagram-p029-29_hu_124eea9e7e287008.jpg) - **Protocol:** Modbus TCP - **Port:** 502 - **Default Slave ID:** 1 - **Hostname:** comfoconnectpro.local (mDNS) ### Connector layout ![Zehnder ComfoConnect PRO connector layout — front, side and bottom view](https://taphome.com/images/compatibility/zehnder-comfoconnect-pro/connector-layout-p007-07_hu_1e2bcba421ab753d.jpg) Key connectors relevant for TapHome integration: | Connector | Function | |-----------|----------| | **Ethernet (RJ45)** | Network connection — Modbus TCP communication with TapHome | | **ComfoNet** | CAN bus cable to the ventilation unit (CAN_H, CAN_L, 12V, GND) | | **Modbus RTU (H, L)** | RS-485 — alternative for BMS integration (not needed for TapHome) | | **USB** | Service connection | | **PSU 12VDC** | Power supply input (12V, 2A max) | ### ComfoNet cable wiring ![Zehnder ComfoConnect PRO ComfoNet cable connection to ventilation unit](https://taphome.com/images/compatibility/zehnder-comfoconnect-pro/wiring-comfonet-p014-14_hu_3df5a7d785b70880.jpg) | Wire Color | Connection | |------------|-----------| | WHITE | CAN_L | | YELLOW | CAN_H | | BLACK | GND | | RED | 12V | ## Enabling Modbus TCP communication Modbus TCP must be enabled through the ComfoConnect PRO web interface before TapHome can communicate with the device. 1. Connect the ComfoConnect PRO to your local network via Ethernet or Wi-Fi 2. Open a browser and navigate to **http://comfoconnectpro.local** (or the device IP address) 3. Log in with username **admin** and the password set during first configuration 4. Navigate to **Configurations > Third Party Settings** 5. Select **Modbus TCP** from the protocol dropdown 6. Keep the default settings — Slave ID: 1, TCP Port: 502 7. Click **Apply** — the device will reboot to apply the new settings > [!WARNING] > Saving Modbus TCP settings will **reboot** the ComfoConnect PRO. The device will be temporarily unavailable during the restart. ## Configuration in TapHome When importing the template in TapHome, provide: - **IP Address** — the ComfoConnect PRO's IP on the local network (check the web interface Network page) - **Slave ID** — Modbus slave address (default: 1) > [!TIP] > The ComfoConnect PRO supports mDNS — it is discoverable as `comfoconnectpro.local`. Assign a static IP address in the router's DHCP settings to prevent the address from changing after a power cycle. ## Device capabilities The template exposes the following devices: ### Ventilation control - **Ventilation (multi-value switch)** — ventilation preset via holding register HR:0. Selects the airflow level: Away (minimum), Low, Medium, High. The ventilation unit adjusts fan speeds according to the selected preset. - **Ventilation Boost** — toggle switch via coil C:6. Activates maximum airflow for a configurable duration (default 2 hours / 7200 seconds set during template initialization via HR:4). Boost is available when auto mode is disabled. - **Airflow** — read-only sensor showing the current supply fan volume flow in m³/h from input register IR:6. ### Temperature and humidity monitoring The template includes four combined temperature and humidity sensors. Temperature values are stored as °C × 10 (Int16, divide by 10), humidity as percentage (Int16, divide by 100). | Sensor | Temp Register | Humidity Register | Description | |--------|---------------|-------------------|-------------| | **Extract** | IR:8 | IR:13 | Air taken from rooms before the heat exchanger | | **Exhaust** | IR:9 | IR:14 | Air leaving the heat exchanger to outside | | **Outdoor** | IR:10 | IR:15 | Fresh air intake | | **Supply** | IR:11 | IR:16 | Heated fresh air delivered to rooms | > [!NOTE] > Room temperature (IR:7) and room humidity (IR:12) are available in the Modbus register map but not included in the template. These require an optional room sensor connected to the ventilation unit. ### Temperature profile - **Temperature Profile (multi-value switch)** — selects the heat exchanger bypass behavior via holding register HR:1. Values: Normal (balanced), Cold (retains more heat), Warm (allows more bypass cooling). ### Filter monitoring - **Filter Dirty** — read-only binary sensor from discrete input DI:3. Indicates when the filter needs replacement or cleaning. - **Filter Days Left** — read-only sensor from input register IR:25. Shows the remaining filter lifetime in days, counting down from the configured filter lifetime. ### Additional register capabilities The ComfoConnect PRO exposes additional Modbus registers not currently included in the TapHome template: | Register | Name | Type | Notes | |----------|------|------|-------| | IR:0 | Connection State | Sensor | 0=OK, 30=not CAQ, 40=version incompatible, 50=no unit | | IR:1–IR:5 | Active Errors 1–5 | Sensor | Error codes (84 defined codes) | | IR:17–IR:24 | CO2 Zones 1–8 | Sensor | ppm, requires optional CO2 sensors | | HR:2 | Temperature Profile Mode | Config | 0=Adaptive, 1=Fixed, 2=External Setpoint | | HR:3 | External Setpoint | Config | °C×10, range 5–35°C | | C:0 | Reset Errors | Action | Self-resetting coil | | C:5 | Auto Mode | Config | Enable/disable automatic ventilation | | C:7 | Away Function | Config | Enable/disable away function | | C:8 | ComfoCool | Config | Enable/disable passive cooling | ## Compatible ventilation units The ComfoConnect PRO works with the following Zehnder ventilation systems: - **ComfoAir Q series** — Q350, Q450, Q600 (ComfoNet compatible) - **ComfoAir Flex** — ComfoNet compatible > [!WARNING] > The **ComfoAir Classic series** (ComfoAir 160/180/200/225/350/450/550, SL220/SL330, Standard 300/375) is **not supported** by the ComfoConnect PRO, despite older Zehnder installer manuals (connecting diagram, page 29) listing these models as "available from software release 1.1". Classic units use a different legacy protocol and previously relied on the now-discontinued ComfoConnect LAN-C or KNX-C modules. The Standard 300 has only a hardware boost input and cannot be remotely controlled at all. For older Classic units, contact Zehnder for current recommendations or consider replacement with a ComfoAir Q or Flex unit. ## Troubleshooting ### No Modbus communication 1. Verify Modbus TCP is enabled in the web interface (Configurations > Third Party Settings) 2. Confirm the ComfoConnect PRO IP address — check http://comfoconnectpro.local or the router's DHCP lease table 3. Ensure TapHome Core and the ComfoConnect PRO are on the same network/subnet 4. Check that no firewall is blocking port 502 5. Verify the ComfoNet LED is solid green — blinking indicates a cable issue between the gateway and the ventilation unit ### Gateway path unavailable error The Modbus exception code 0x0A (GatewayPathUnavailable) indicates the ComfoConnect PRO cannot reach the ventilation unit over ComfoNet. Check the ComfoNet cable connections and verify the ventilation unit is powered on. ### Boost mode not responding Boost mode via coil C:6 only works when Auto Mode (coil C:5) is disabled. The template initialization script disables Auto Mode automatically, but if it was re-enabled manually, boost commands will be ignored. ## Available devices ComfoConnect PRO Module Airflow Variable Read-only Supply fan volume flow in m³/h Register: IR:6 Int16 Unit: m³/h Exhaust Temperature & Humidity Temperature Sensor Read-only Exhaust air temperature and humidity — air leaving the heat exchanger to outside Register: IR:9 (temp), IR:14 (hum) Int16 Unit: °C / % scaled Extract Temperature & Humidity Temperature Sensor Read-only Extract air temperature and humidity — air taken from rooms before the heat exchanger Register: IR:8 (temp), IR:13 (hum) Int16 Unit: °C / % scaled Filter Dirty Reed Contact Read-only Filter replacement or cleaning warning Register: DI:3 Bool boolean Outdoor Temperature & Humidity Temperature Sensor Read-only Outdoor air temperature and humidity at the fresh air intake Register: IR:10 (temp), IR:15 (hum) Int16 Unit: °C / % scaled Supply Temperature & Humidity Temperature Sensor Read-only Supply air temperature and humidity — heated fresh air delivered to rooms Register: IR:11 (temp), IR:16 (hum) Int16 Unit: °C / % scaled Temperature Profile Multi-value Switch Heat exchanger bypass behavior — Normal, Cold (retains more heat), Warm (allows more bypass cooling) Register: SH:1 Int16 numeric Values / States: Normal · Cold · Warm Ventilation Multi-value Switch Ventilation preset — Away (minimum), Low, Medium, High Register: SH:0 Int16 numeric Values / States: Away · Low · Medium · High Filter Days Left Variable Read-only Remaining filter lifetime in days Register: IR:25 Int16 Unit: days Ventilation Boost Switch Maximum airflow for a configurable duration (default 2 hours) Register: C:6 Bool boolean Values / States: ON · OFF **Connection:** Modbus TCP • Slave ID: $\[SlaveId] • Hostname: `comfoconnectpro.local` Possible improvements (16) - IR:0 Connection State — UINT16, 0=ok, 30=not CAQ, 40=version incompatible, 50=no unit detected - IR:1–IR:5 Active Errors 1–5 — UINT16, error codes (84 defined codes from 0=NO\_ERR to 104=CO2\_SENS\_GENERAL\_ERR) - IR:7 Room Temperature — INT16, °C\*10, requires optional room sensor - IR:12 Room Humidity — UINT16, %, requires optional room sensor - IR:17–IR:24 CO2 Sensor Zones 1–8 — UINT16, ppm, requires optional CO2 sensors - HR:2 Temperature Profile Mode — UINT16, 0=Adaptive, 1=Fixed, 2=External Setpoint, R/W - HR:3 External Setpoint — UINT16, °C\*10, range 5–35°C, R/W - HR:4 Boost Time — UINT16, seconds, 65535=24 hours. Already used in boost init script but not exposed as separate device - DI:0 Error Flag — Bool, general error indicator - DI:1 Standby — Bool, standby state - DI:2 ComfoHood — Bool, ComfoHood cooker hood active - C:0 Reset Errors — Self-resetting coil, write to clear active errors - C:1–C:4 Ventilation Preset Coils (Away/1/2/3) — Individual coils for each preset. Only true writes accepted — false is ignored - C:5 Auto Mode — Bool, enable/disable automatic ventilation mode - C:7 Away Function — Bool, enable/disable away function - C:8 ComfoCool — Bool, enable/disable passive cooling ## Sources - Zehnder ComfoConnect PRO — Installer Manual [zehnder.lv](https://zehnder.lv/wp-content/uploads/2024/12/ComfoConnect-PRO-Installer-manual.pdf) 2026-03-21 [PDF](https://taphome.com/compatibility/devices/zehnder-comfoconnect-pro/manufacturer/installer-manual.pdf) ## Related Documentation - [Modbus Integration](https://taphome.com/en/compatibility/modbus-guide/) - [Modbus](https://taphome.com/en/docs/integration/modbus/) - [Simple configuration using templates](https://taphome.com/en/docs/integration/modbus/templates/) - [Modbus scripts and prefetch](https://taphome.com/en/docs/script/modbus-scripts/) - [Modbus functions](https://taphome.com/en/docs/script/modbus/) - [Modbus data types](https://taphome.com/en/docs/script/modbus-data-types/)