The Wolf CWL-2 is a comfort ventilation unit with heat recovery for dwellings (for example the CWL-2-400 with a maximum capacity of 400 m³/h). Its base control board UWA2-B has its own Modbus connector X15 and communicates over Modbus RTU on RS-485. The template connects TapHome directly to this connector — no gateway is needed — and covers remote control of ventilation (mode presets or a direct air flow), the unit status, temperatures and humidity, the bypass, the external heater, filter management, the flow settings and diagnostics.
The device names in the template are in Slovak. Where a device is named below, its English description is followed by the exact template name in quotation marks, for example Modbus control (“Riadenie Modbus”).
What the template covers
The template is written for the standard unit with only the base board UWA2-B, connected on X15.
- Plus version (Plus board UWA2-E): when the unit is supplied as a Plus version, Wolf specifies that the Modbus connection is made on connector X06 of the UWA2-E instead, and X15 of the base board is then used to connect the Plus board. The inputs, outputs and the geo heat exchanger of the Plus board are not part of the template.
- Cascade: when several Wolf units are cascaded, the Modbus connection must go to the master unit with a Plus board — this setup is not covered either.
- CO2 sensors: the optional eBus CO2 sensors (up to four) and their settings are not read by the template.
- Modbus settings: the bus type, slave address and baud rate are set on the unit’s touchscreen (steps 14.1–14.4, see below), not from TapHome.
Hardware connection
Before working on the unit, always disconnect it from the mains by pulling the power plug.
Modbus connector X15
X15 is the red 3-pole connector on the base board UWA2-B. It carries RS-485 A, RS-485 B and RS-485 ground (connection A in the figure above).
- Disconnect the unit from the mains.
- Connect RS-485 A and RS-485 B of X15 to A and B of the TapHome RS-485 bus, and RS-485 ground to the bus ground (GND).
- Set the terminating resistor and the jumpers on the UWA2-B as described below.
- Connect the unit to the mains again.
Terminating resistor and jumpers
- X12 is the jumper of the 120 Ω Modbus terminating resistor. Remove it when the bus is already terminated elsewhere — that is, when the CWL-2 is not at the end of the RS-485 line.
- For a Modbus application, the electrical diagram also says to remove the jumpers X121 and X122 on the UWA2-B. All three jumpers X12, X121 and X122 are placed only when the connector is used for the Wolf external bus or for a Plus board.
Configuration on the unit
Modbus settings (steps 14.1–14.4)
The Modbus settings are in the settings menu of the unit’s touchscreen (the settings icon on the main screen), group 14 Communication:
| Step | Setting | Factory setting | Range |
|---|---|---|---|
| 14.1 | Type of bus connection | ModBus | Off / ModBus / external Bus |
| 14.2 | Slave address | 20 | 1–247 |
| 14.3 | Baud rate | 19k2 | 1200 / 2400 / 4800 / 9600 / 19k2 / 38k4 / 56k / 115k2 |
| 14.4 | Parity | Even | No / Even / Odd |
At factory settings the unit is already a Modbus slave with address 20. Check that 14.1 is set to ModBus, and give the unit a unique address when other Modbus devices share the bus.
The template uses the factory communication parameters:
| Parameter | Value |
|---|---|
| Baud rate | 19200 |
| Parity | Even |
| Data bits | 8 |
| Stop bits | 1 |
| Slave ID | 20 (import parameter Modbus Slave ID) |
In TapHome, the template is imported on a Modbus RTU interface on this RS-485 bus, with the Slave ID set to the address from step 14.2.
Enabling remote control
After the import, the unit only accepts ventilation commands when Modbus control (“Riadenie Modbus”, register 8000) is switched on:
- Switch (“Prepínač”) — the ventilation mode is selected with Requested mode (“Požadovaný režim”): Holiday, Low, Normal or High.
- Flow (“Prietok”) — the air flow is set directly in m³/h with Requested flow (“Požadovaný prietok”).
- Off (“Vypnuté”) — remote control is off (default).
After the unit has been disconnected from the mains, the remote control registers 8000–8011 and the requested air flow must be set again — Modbus control returns to Off.
While Modbus is active, the ventilation mode can no longer be changed on the unit’s display or with a connected multiple switch, and a connected humidity sensor does not work.
Device capabilities
Ventilation control
- Modbus control (“Riadenie Modbus”) — Off, Switch or Flow (see above).
- Requested mode (“Požadovaný režim”) — Holiday, Low, Normal or High; effective when Modbus control is set to Switch. The device also has the service action Reset device (“Reset zariadenia”), which sends an appliance reset to the unit.
- Requested flow (“Požadovaný prietok”) — air flow in m³/h, between the minimum and maximum flow of the unit type; effective when Modbus control is set to Flow.
- Standby (“Pohotovostný režim”) — puts the unit into standby or back into normal mode. The value read back is the actual standby state, which can also be changed from other interfaces of the unit.
Unit status
- Active function (“Aktívna funkcia”) — the function the unit is running, read only. The template names Standby, Manual, Holiday, Night ventilation, Party and Bypass boost; the unit can also report other functions (for example errors, Auto CO2 or Auto Modbus) that the template does not name.
- Current ventilation mode (“Aktuálny režim vetrania”) — Holiday, Low, Normal, High or Automatic, read only. Service attributes: the fan control type and the position of a connected flow switch.
- Supply air pressure and Exhaust air pressure (“Tlak privádzaného vzduchu”, “Tlak odvádzaného vzduchu”) — duct pressures in Pa.
Temperature and humidity
- Supply air – temperature and humidity (“Privádzaný vzduch – teplota a vlhkosť”) and Exhaust air – temperature and humidity (“Odvádzaný vzduch – teplota a vlhkosť”) — the sensors at the supply and exhaust fan. Each has service attributes with the fan status, the set and actual flow (m³/h), the mass flow (kg/h), the fan speed and the anemometer speed (RPM).
- NTC1 temperature and NTC2 temperature (“Teplota NTC1”, “Teplota NTC2”) — the two NTC sensors of the unit.
- Relative humidity (RHT) (“Relatívna vlhkosť (RHT)”) — the value of the RHT humidity sensor in %.
Bypass
Bypass – mode (“Bypass – režim”) switches the 100 % bypass between Automatic, Closed and Open. Its service attributes show the bypass state (initializing, opening, closing, open, closed), the step position of the valve, the two opening temperatures and the hysteresis. Service actions set:
| Service action | Range |
|---|---|
| Opening temperature, indoor air (“Nastaviť teplotu otvárania (interiér)”) | 15.0–35.0 °C |
| Opening temperature, outdoor air (“Nastaviť teplotu otvárania (vonkajšia)”) | 7.0–15.0 °C |
| Bypass hysteresis (“Nastaviť hysterézu bypasu”) | 0.0–5.0 °C |
In automatic mode the bypass opens when the outdoor air is warmer than the outdoor threshold, cooler than the air from the dwelling, and the air from the dwelling is warmer than the indoor threshold. It closes when the outdoor air drops below the outdoor threshold, becomes warmer than the indoor air, or the indoor air drops below the indoor threshold minus the hysteresis.
Bypass boost switches the bypass boost function on or off: with the bypass open, the unit runs at the flow preset shown in the service attribute Flow preset at boost (factory setting High).
External heater and frost protection
External heater (“Vonkajší ohrievač”) sets the mode of an external heater: Not available, Pre-heater or Post-heater. Its service attribute shows the post-heater set temperature.
Frost protection is read through service attributes of the module: preheater status and capacity, frost heater power, fan reduction during frost protection, the frost control temperature and the minimum supply temperature during frost protection. The template only reads these two temperatures; they are set on the unit’s display (steps 3.1 and 3.2).
Filter
- Filter – status (“Filter – stav”) — Clean or Dirty. Service attributes: operating hours, days since the last filter change, flow since the filter change and total flow since commissioning. The service action Reset filter warning (“Resetovať upozornenie filtra”) confirms the filter change.
- Filter change interval (“Interval výmeny filtra”) — days until the filter message, 1–365 (factory setting 90).
Flow settings
- Flow preset – Holiday, – Low, – Normal and – High (“Predvoľba prietoku – Prázdniny / Nízky / Normálny / Vysoký”) — air flow of the four ventilation modes in m³/h. The limits depend on the unit type, and each preset must stay between the neighbouring ones (Holiday ≤ Low ≤ Normal ≤ High).
- Flow control type (“Typ riadenia prietoku”) — Constant PWM, Constant flow (factory setting) or Constant mass flow.
- Fan imbalance (“Nevyváženosť ventilátorov”) — allows or forbids imbalance. Service attributes: the imbalance value (supply increased against exhaust, in %) and the supply and exhaust offsets.
- 💨 Total fan power ("💨 Celkový výkon ventilátora") and 💨 Exhaust – power (%) ("💨 Odvod – výkon (%)") — write the PWM presets of fan setting 2 (Normal) for the supply and exhaust fan (registers 6014 and 6015). The first device writes both fans at once. According to the Modbus documentation the PWM presets range from 15 to 100 %; they apply when the flow control type is Constant PWM.
- 💨 Supply – speed (RPM) and 💨 Exhaust – speed (RPM) ("💨 Prívod – otáčky (RPM)", “💨 Odvod – otáčky (RPM)”) — fan speeds.
Diagnostics
The module has service attributes with the software and hardware version of the base board, the appliance type, the DIP switch value, the serial number (three BCD groups), the current time and date, the eBus power status and the signal output (0 V / 24 V). The time is shown as a raw number: according to the Modbus documentation the high byte holds the hours and the low byte the minutes.
The module raises an error when frost protection reports an error, a warning when the supply or exhaust fan does not communicate, and an error when a fan is blocked or reports a fault.
Troubleshooting
- No communication: check that step 14.1 is set to ModBus, that the slave address (14.2), baud rate (14.3) and parity (14.4) match the import parameter and the interface settings in TapHome, that A and B are not swapped, and that the jumpers X121 and X122 are removed. Remove X12 when the bus is already terminated.
- The unit ignores commands from TapHome: Modbus control must be set to Switch (for Requested mode) or Flow (for Requested flow). After a mains failure it is Off again and must be set once more.
- The mode cannot be changed on the unit’s display: this is expected while Modbus control is active.
- Fault E123 (sub-code E2400) on the display: external Modbus fault — operation via Modbus does not work. Wolf advises checking the cabling and the connected accessories.
- The bypass does not open: in automatic mode check the opening temperatures and the hysteresis in the service attributes of Bypass – mode, and that the outdoor air is cooler than the air from the dwelling.
- The filter message stays on after a filter change: run the service action Reset filter warning on Filter – status, or reset the filter at step 4.3 on the unit.
