TapHome

2VV Daphne

Modbus RTU
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Last updated: 03. 2026
2VV Daphne

The 2VV Daphne is a heat recovery unit (HRU) controlled by the AirGENIO system. This TapHome template connects to the unit via Modbus RTU over RS-485 and provides airflow control, three temperature sensors, filter monitoring, temperature sensor selection, and a manual/automatic temperature control switch.

The AirGENIO Modbus guide covers all 2VV products (air curtains with COMFORT, SUPERIOR, or IC controls, SC controllers, and HRU/AHU units). The Daphne uses the HRU register subset (green rows in the Modbus XLS spreadsheet).

Hardware connection

RS-485 wiring

The AirGENIO control board has RS-485 terminals marked A and B. The exact pin positions depend on the control board type installed in the unit.

COMFORT controls (module-B) — RS-485 terminals: B (pin 25), A (pin 24), GND (pin 23)

COMFORT controls (module-B) main board — RS-485 terminals B (pin 25), A (pin 24), GND (pin 23)

SUPERIOR, IC, SC controls (module-A) — RS-485 terminals: A (pin 25), B (pin 26), GND (pin 28). This board also has an Ethernet port for Modbus TCP.

SUPERIOR, IC, SC controls (module-A) main board — RS-485 terminals A (pin 25), B (pin 26), GND (pin 28), and TCP Ethernet port

Connect to TapHome RS-485:

  • A on AirGENIO → A+/D+ on TapHome
  • B on AirGENIO → B-/D- on TapHome
  • GND on AirGENIO → GND on TapHome

Important — Polarity

Inverting the A and B connections can prevent communication and may also stop the entire system due to incorrect polarisation voltage on the terminals. Use consistent cable colors (e.g., white for A, blue for B) across all devices.

Cable specification
  • Type: shielded twisted pair (telephone type), e.g. Belden 3105A
  • Max cable length: 150 m (up to 700 m with Belden 3105A)
  • Max devices on bus: 32 (including repeaters)
  • Shield must be earthed at one point only (one end of main cable)
  • Use a twisted pair for A/B and a separate wire for GND
Bus topology
RS-485 daisy-chain bus topology for 2VV AirGENIO devices

Devices are connected in a daisy-chain configuration. The main boards (module-B, module-A) already include a built-in terminating resistor.

Configuration

Modbus RTU settings

To configure communication parameters, enter the service menu on the AirGENIO control panel using code 1616, then navigate to 20 - Modbus RTU. The Modbus RTU settings screen allows you to configure the slave address (1–247, default 1), baud rate (9600 default), and parity.

AirGENIO service menu: Service (code 1616) → 20 - Modbus RTU → Address, Baudrate, Parity settings

Parity mismatch — verify before connecting

The TapHome XML template specifies Even parity, but the PDF manual states the default is ODD parity. Before connecting, check the parity setting on the unit (service menu 20, code 1616). If communication fails, try switching between Even and ODD parity in TapHome module settings.

The parity can also be changed via Modbus register H:25023 (0=None, 1=ODD, 2=Even).

Network settings (Modbus TCP)

For SUPERIOR, IC, and SC controls only — navigate to 21 - Network to configure IP address, subnet mask, gateway, and DHCP settings for Modbus TCP communication.

AirGENIO service menu: Service (code 1616) → 21 - Network → DHCP, IP address, Mask, Gateway settings
Software reset after changes

After any changes in menu 20 - Modbus RTU or 21 - Network, a software reset is required. Navigate to 48 - Software reset and confirm with SW RESET.

AirGENIO service menu: Service (code 1616) → 48 - Software reset → SW RESET confirmation

A software reset is mandatory after changing Modbus RTU or Network settings. The unit will restart and apply the new communication parameters.

Technical specifications
ParameterValue
ProtocolModbus RTU Slave, RS-485
Baud rate9600 (default)
ParityODD (default) / Even (template)
Stop bits1
Data bits8
Slave ID1–247 (default 1)
Max cable length150 m (700 m with Belden 3105A)
Max bus devices32

Device capabilities

Airflow control

Air Flow Manual controls the unit’s fan speed as a continuous dimmer value (0–100%). The template reads the ON/OFF state from H:21000 and the flow level from H:21001 (value in permille, 0–1000). Writing a level greater than 0 sets the flow and turns the unit ON; writing 0 turns the unit OFF.

Two service attributes show the calibrated airflow limits:

  • Max Flow Manual (H:10110) — maximum airflow after calibration
  • Min Flow Manual (H:10111) — minimum airflow after calibration
Temperature monitoring

The template provides three temperature sensors that read from input registers with automatic division by 10:

  • Outdoor Temperature (A:18006) — outdoor temperature sensor (device type 3003 with security capability)
  • Outlet Air Temperature (A:18007) — outside/exhaust air temperature (TempEXT1 in the manual)
  • Inlet Air Temperature (A:18008) — supply air temperature after heat recovery (TempEXT3 in the manual)

The template names “Inlet air” and “Outlet air” refer to the building perspective: inlet = fresh air entering the building (after heat exchange), outlet = exhaust air leaving the building. The manual uses sensor names TempEXT3 and TempEXT1 respectively.

Filter monitoring

Filter Status (A:18015) shows the filter condition as a percentage value. Two service attributes provide detailed tracking:

  • Filter Working Hours (H:25018) — current filter operating hours (0–3000)
  • Filter Max Hours (H:25019) — maximum hours before replacement (200–3000, default 1440)

When the working hours approach the maximum, plan a filter replacement to maintain air quality and unit efficiency.

Temperature control configuration

Temperature Sensor Selection (H:25008) selects which sensor is used for temperature regulation:

ValueSensorTemperature range
0Supply duct15–45°C
1Extract duct15–30°C
2Room15–30°C
3Thermostat—
4Room BMS—

Temperature Control Mode (H:25032) switches between:

  • Manual (OFF) — direct control of heater output
  • Automatic (ON) — automatic temperature regulation based on the selected sensor

Both registers are in the SERVICE_HARD group, meaning they are not affected by factory reset.

Additional capabilities

The AirGENIO system also supports temperature setpoint control (H:21003), inlet air temperature sensor (A:18009), water return temperature (A:18010), room temperature (A:18011), heater power output (A:18013), filter percentage (A:18016), unit status word (A:18000), error bitmask (A:18001), sensor status (A:18003), and day/night mode switching (H:21009). These can be added in a future template update.

The temperature setpoint register (H:21003) is not included in the current template. To control the setpoint, it can be added as a custom Modbus device in TapHome using register H21003 with value in °C.

Troubleshooting

No Modbus communication
  1. Verify parity setting — the most common issue. The template uses Even parity, but the unit default is ODD. Check service menu 20 or try both settings in TapHome
  2. Check RS-485 cables:
    • A on AirGENIO correctly connected to A+/D+ on TapHome
    • B on AirGENIO correctly connected to B-/D- on TapHome
    • GND connected between AirGENIO and TapHome
  3. Verify the Modbus Slave address matches between the unit and TapHome (default: 1)
  4. Confirm TapHome is set to: 9600 baud, 1 stop bit, 8 data bits
  5. After any Modbus setting changes on the unit, perform a software reset (Service → 48 → SW RESET)
Communication works but values are wrong
  1. Check temperature scaling — all temperature registers use division by 10 (not 100 as in some other devices)
  2. Verify the register addresses use PLC addressing (BASE+1) — the manual uses PLC addresses while the template uses raw Modbus addresses (one less)
  3. For airflow, values are in permille (0–1000), not percentage
Filter alarm
  1. Check Filter Working Hours (H:25018) vs Filter Max Hours (H:25019) in service attributes
  2. Clean or replace the filter
  3. Reset the filter counter after replacement via the unit’s control panel

Available devices

2VV Daphne Module
Air Flow Manual Dimmer

Manual airflow control — sets fan speed as a percentage (0–100%), reads ON/OFF state and flow level in permille

Register: H:21000, H:21001 → H:21001, H:21000 Bool + UInt16 Unit: ‰ compound
Service Attributes
Max Flow ManualMaximum airflow limit after fan calibration
Min Flow ManualMinimum airflow limit after fan calibration

Air Flow Manual

Read level
var st := MODBUSR(H, 21000, Bool);
var va := MODBUSR(H, 21001, Uint16) / 1000;

if st = 1
	return(va);
else
	return(st);
end
Write level
if Le > 0
	MODBUSW(H, 21001, Uint16, Le * 1000);
	MODBUSW(H, 21000, Uint16, 1);
else
	MODBUSW(H, 21000, Uint16, 0);
end
Service Attributes
Max Flow Manual
modbusr(H, 10110, Uint16) / 10
Min Flow Manual
modbusr(H, 10111, Uint16) / 10
Filter Status Analog Input Read-only

Filter condition indicator with working hours tracking and configurable replacement interval

Register: A:18015 UInt16 Unit: % numeric
Service Attributes
Filter Working HoursCurrent filter operating hours (0–3000)
Filter Max HoursMaximum filter hours before replacement (200–3000, default 1440)

Filter Status

Read input level
MODBUSR(A, 18015, Uint16) / 100
Service Attributes
Filter Woring Hours
modbusr(H, 25018, Uint16)
Filter Max Hours
modbusr(H, 25019, Uint16)
Inlet Air Temperature Temperature Sensor Read-only

Supply air temperature after heat recovery — fresh air entering the building

Register: A:18008 Int16 Unit: °C numeric

Inlet Air Temperature

Read temperature
MODBUSR(A, 18008, Int16) / 10
Outlet Air Temperature Temperature Sensor Read-only

Exhaust air temperature leaving the building (outside air sensor TempEXT1)

Register: A:18007 Int16 Unit: °C numeric

Outlet Air Temperature

Read temperature
MODBUSR(A, 18007, Int16) / 10
Temperature Sensor Selection Multi-value Switch

Selects which temperature sensor is used for automatic temperature regulation

Register: H:25008 UInt16 numeric
Values / States: Supply duct · Extract duct · Room · Thermostat · Room BMS

Temperature Sensor Selection

Read switch state
MODBUSR(H, 25008, Uint16)
Write switch state
MODBUSW(H, 25008, Uint16, Mu)
Temperature Control Mode Switch

Switches between manual heater control and automatic temperature regulation based on the selected sensor

Register: H:25032 Bool
Values / States: Automatic · Manual

Temperature Control Mode

Read switch state
MODBUSR(H, 25032, Bool)
Write switch state
MODBUSW(H, 25032, Bool, St)
Outdoor Temperature Temperature Sensor Read-only

Outdoor temperature sensor with security monitoring capability

Register: A:18006 Int16 Unit: °C numeric

Outdoor Temperature

Read temperature
MODBUSR(A, 18006, Int16) / 10
Connection: Modbus RTU • 9600 baud• 8E1 • Slave ID: $[SlaveId]
Possible improvements (12)
  • H:21003 Temperature Setpoint — Temperature setpoint in °C — used in all usage examples for automatic temperature control
  • A:18009 Inlet Air Temperature (TempINT1) — Inlet air temperature sensor (INT1), scale /10 °C. Range -40 to 100°C
  • A:18010 Water Return Temperature (TempWOut) — Water return temperature for water heater models, scale /10 °C
  • A:18011 Room Temperature (TempRoom) — Room temperature from CT-ROOM sensor, scale /10 °C
  • A:18013 Heater Power — Heater output power in %, range 0–100
  • A:18016 Filter Percentage — Filter wear percentage (0–100%). More direct than the current A:18015 reading
  • A:18000 Unit Global Status — 16-bit status word — ON/OFF, auto heat, auto flow, night reduction, door contact, antifreeze, summer/winter etc.
  • A:18001 Software Error — Error bitmask — fan error, filter error/warning, heater error, DX error, global error, config file error
  • A:18003 Sensor Status — Sensor OK/ERROR bitmask for all temperature sensors (outside, outlet, inlet, water return, room, BMS)
  • H:21009 Day/Night Mode — Day/Night switching: 0=Day, 1=Night. Used with SC controls
  • H:23002 BMS Outside Temperature — Write outside temperature from BMS (must write every 30s). Requires H:20044=1 to enable
  • H:25033 Temperature Control Mode (direct register) — Same function as H:25032 in template but using the documented register address. 0=manual, 1=automatic
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