---
title: "Daikin FWEC3"
description: "Control fan coil modes, temperature setpoints, and fan speed via Modbus RTU. TapHome integration template for Daikin FWEC3 Advanced Plus LCD controller."
url: "https://taphome.com/en/compatibility/daikin-fwec3/"
language: en
lastmod: 2026-10-08
generator: hugo
ai:
  topics: ["modbus-rtu","air-conditioning","rs485","fan-coil","supervisor-control"]
  questions: ["How to integrate Daikin FWEC3 fan coil controller with TapHome?","What does the Daikin FWEC3 TapHome template control?","How to connect Daikin FWEC3 via RS-485 to TapHome?","Why does the Daikin FWEC3 not respond to mode or setpoint changes from TapHome?","How to enable supervisor control on the Daikin FWEC3?","What fan speed options are available for the Daikin FWEC3 in TapHome?"]
---

# Daikin FWEC3

Communication: Modbus RTU

- [Daikin Official Website](https://www.daikin.com)

## Integration guide

The Daikin FWEC3 (model FWEC3A) is an Advanced Plus LCD electronic controller for indoor fan coil units. It communicates via Modbus RTU over RS-485 and provides control of operating mode, temperature setpoints, fan speed, and unit on/off state through TapHome.

The controller supports 2-pipe and 4-pipe fan coil systems with up to 38 system configurations (parameter P00), 3 or 4 fan speeds or modulating fan operation, and optional water temperature monitoring. A master-slave RS-485 network supports up to 247 slave controllers.

## Hardware connection

### RS-485 wiring

The FWEC3 electronic board provides RS-485 terminals labeled **A(-)**, **B(+)**, and **GND** for Modbus RTU communication.

Connect using a 3-wire RS-485 connection:

- **A(-)** on FWEC3 → B-/D- on TapHome RS-485
- **B(+)** on FWEC3 → A+/D+ on TapHome RS-485
- **GND** on FWEC3 → GND on TapHome power supply (**mandatory**)

**Cable specification:**

- Type: AWG 24, shielded 2-conductor cable (0.511 mm diameter)
- Termination resistor required on both ends of the RS-485 bus (master-slave setup)
- Ground the shield at one end only to avoid ground loops

> [!WARNING]
> The GND wire **must** be connected between the FWEC3 controller and TapHome. Without proper grounding, communication errors will occur. Use single-point grounding for the cable shield.

### Wiring diagram

![Daikin FWEC3 wiring diagram — 2-pipe 3-speed configuration with RS-485 terminals](https://taphome.com/images/compatibility/daikin-fwec3/wiring-2pipe-3speed_hu_a72e223a275ed0c3.jpg)

The top diagram shows a typical 2-pipe, 3-speed fan coil wiring with the FWEC3 controller. The RS-485 bus terminals (A, B, GND) are located on the lower-left area of the electronic board, alongside sensor inputs (SA, SW, SU) and digital/analog outputs.

![Daikin FWEC3 wiring diagram — 4-pipe configuration with EPIMSB6 expansion board](https://taphome.com/images/compatibility/daikin-fwec3/wiring-4pipe-epimsb6_hu_969c55584da4df45.jpg)

The bottom diagram shows a 4-pipe configuration using the EPIMSB6 expansion board for additional valve and motor outputs. The RS-485 connection remains on the main FWEC3 board.

## Configuration

### Modbus address (P02)

The Modbus slave address is configured via parameter **P02** on the controller:

1. Switch the thermostat **off**
2. Press the **Up** and **Down** keys simultaneously to enter the password screen
3. Enter password **10** and confirm
4. Scroll to parameter **P02**
5. Set the desired Modbus address (1–254 for slave, 255 for master)
6. Confirm and exit configuration mode

The default slave address is **1**. After changing P02, power-cycle the controller for the new address to take effect.

### Communication parameters

The FWEC3 uses fixed communication settings that must match the TapHome Modbus RTU CCU configuration:

| Parameter | Value |
|-----------|-------|
| Baud rate | 9600 |
| Parity | None |
| Data bits | 8 |
| Stop bits | 2 |

### Supervisor enable pattern

The FWEC3 uses a **supervisor enable pattern** on register H:50. Each control function (on/off, mode, setpoint, fan speed) has a dedicated enable bit in the high byte of H:50. The corresponding control bit in the low byte has **no effect** until its enable bit is set.

The TapHome template includes four **service actions** on the module level to enable supervisor control:

| Service action | Bit | What it enables |
|----------------|-----|-----------------|
| Enable On/Off supervisor | H:50 bit 8 | Unit on/off control via State device |
| Enable mode supervisor | H:50 bit 9 | Cool/Heat mode switching via Mode device |
| Enable setpoint supervisor | H:50 bit 13 | Temperature setpoint override via Thermostat |
| Enable fan speed supervisor | H:50 bit 15 | Fan speed control via Fan Speed device |

> [!WARNING]
> After importing the template, **run all four service actions** before attempting to control the fan coil unit. Without enabling the supervisor bits, write commands from TapHome are silently ignored by the controller.

## Device capabilities

### Operating mode and state control

- **Mode** — selects the operating mode: Cool, Heat, Fan, or Dry. Reads bit 1 of the status register (A:0) and writes control bit 1 in H:50 (enabled by supervisor bit 9). A service attribute shows whether mode supervision is currently enabled.
- **State** — turns the fan coil unit on or off. Reads bit 0 of the status register (A:0) and writes control bit 0 in H:50 (enabled by supervisor bit 8). A service attribute shows whether on/off supervision is currently enabled.

### Temperature monitoring and control

- **Thermostat** — provides room temperature regulation. Reads the current room temperature from A:2, the current setpoint from A:8, and room humidity from A:3. The write script automatically selects the correct setpoint register based on the current operating mode: H:52 for cooling or H:53 for heating. Service attributes expose the setpoint supervision status and the minimum/maximum setpoint limits for both cooling (H:54–H:55) and heating (H:56–H:57).
- **Water Temperature** — reads the water pipe temperature from register A:4 with automatic division by 100 for conversion to degrees Celsius. This sensor is only available when a water temperature probe is installed (parameter P04=1).

### Fan speed control

- **Fan Speed** — selects from five speed levels: Off, Very low, Low, Medium, and High (values 0–4). Reads the current speed from A:1 and writes to H:58. For units with modulating fan control, H:58 accepts a percentage value instead. Service attributes show the modulating fan mode (Off, Manually forced, Automatic) from H:60, and whether fan speed supervision is enabled.

### Additional capabilities

The FWEC3 controller also exposes registers for the active temperature setpoint (A:7), system configuration readback (A:5), analog output monitoring (A:15–A:16), economy mode with setpoint correction (H:50 bit 3 + H:59), hourly programming schedules (H:51), keypad lock (H:50 bit 5), and dehumidification status (A:0 bit 12). These can be added in a future template update.

> [!TIP]
> The module ReadScript monitors bit 5 of the status register (A:0) and reports a "General alarm on unit" error in TapHome when an alarm condition is detected on the fan coil unit.

## Troubleshooting

### Controller does not respond to mode/setpoint/fan changes

This is the most common issue. The supervisor enable bits in H:50 must be set before BMS control works:

1. Open the Daikin FWEC3 module in TapHome
2. Run all four **service actions**: Enable On/Off supervisor, Enable mode supervisor, Enable setpoint supervisor, Enable fan speed supervisor
3. Retry the control command

### No Modbus communication

1. **Check RS-485 wiring:** Verify A(-), B(+), and GND are correctly connected and the GND wire is present
2. **Verify slave address:** Confirm parameter P02 matches the Slave ID configured in TapHome (default: 1)
3. **Check communication settings:** TapHome must be set to 9600 baud, no parity, 8 data bits, **2 stop bits** (note: 2 stop bits, not 1)
4. **Termination resistor:** For long bus runs or multiple units, ensure termination resistors are present at both ends of the RS-485 bus

### Water temperature reads zero

The water temperature sensor (A:4) requires a physical water probe to be installed and parameter P04 to be set to 1 (available). If P04=0, the register returns 0.

### Thermostat writes to wrong setpoint register

The template automatically selects H:52 (cooling) or H:53 (heating) based on the current mode bit (A:0 bit 1). If the mode changes between writing setpoints, the setpoint may be written to the previous mode's register. Ensure the mode is stable before adjusting the setpoint.

## Available devices 5

These devices appear in TapHome after import.

Daikin FWEC3 Module

Service Actions

|                             |
|-----------------------------|
| Enable On/Off supervisor    |
| Enable mode supervisor      |
| Enable setpoint supervisor  |
| Enable fan speed supervisor |

Read (module)

```taphome
IF(GETBIT(MODBUSR(A, 0, Uint16),5) = 1, ADDERROR("General alarm on unit"));
```

Service Actions

Enable On/Off supervisor

```taphome
var reg:= MODBUSR(H, 50, Uint16);
MODBUSW(H, 50, UInt16, SETBIT(reg,8,1));
```

Enable mode supervisor

```taphome
var reg:= MODBUSR(H, 50, Uint16);
MODBUSW(H, 50, UInt16, SETBIT(reg,9,1));
```

Enable setpoint supervisor

```taphome
var reg:= MODBUSR(H, 50, Uint16);
MODBUSW(H, 50, UInt16, SETBIT(reg,13,1));
```

Enable fan speed supervisor

```taphome
var reg:= MODBUSR(H, 50, Uint16);
MODBUSW(H, 50, UInt16, SETBIT(reg,15,1));
```

Mode Multi-value Switch Read and write

Operating mode selector — Cool, Heat, Fan, or Dry

Register: A:0 (bit 1) → H:50 (bit 1) UInt16 bitmask

Values / States: Cool · Heat

Read switch state

```taphome
GETBIT(MODBUSR(A, 0, UInt16),1);
```

Write switch state

```taphome
var reg := MODBUSR(H, 50, UInt16);
MODBUSW(H, 50, UInt16, SETBIT(reg,1,Mu));
```

Service Attributes

Set mode supervision enabled

```taphome
Switch(GETBIT(MODBUSR(H, 50, Uint16),9), 0, "Disabled", 1, "Enabled","Unknown");
```

State Switch Read and write

Unit On/Off control — turns the fan coil unit on or off

Register: A:0 (bit 0) → H:50 (bit 0) UInt16 bitmask

Values / States: ON · OFF

Read switch state

```taphome
GETBIT(MODBUSR(A, 0, Uint16), 0);
```

Write switch state

```taphome
var reg := MODBUSR(H, 50, UInt16);
MODBUSW(H, 50, UInt16, SETBIT(reg,0,St));
```

Service Attributes

On/Off supervision control enabled

```taphome
Switch(GETBIT(MODBUSR(H, 50, Uint16),8), 0, "Disabled", 1, "Enabled","Unknown");
```

Water Temperature Temperature Sensor Read-only

Water pipe temperature sensor — available only when water probe is installed (P04=1)

Register: A:4 UInt16 Unit: °C numeric

Read temperature

```taphome
MODBUSR(A, 4, UInt16) / 100
```

Thermostat Thermostat Read and write

Room temperature regulation with humidity — reads current temperature, setpoint, and humidity; writes cooling or heating setpoint based on current mode

Register: A:2 (current temp), A:8 (desired temp), A:3 (humidity) → H:52 (cooling setpoint) / H:53 (heating setpoint) UInt16 Unit: °C numeric

Service Attributes

|                                          |
|------------------------------------------|
| Setpoint temperature supervision enabled |
| Minimum setpoint cool                    |
| Maximum setpoint cool                    |
| Minimum setpoint heat                    |
| Maximum setpoint heat                    |

Read temperature

```taphome
MODBUSR(A, 2, Uint16) / 10
```

Read desired temperature

```taphome
MODBUSR(A, 8, Uint16) / 10
```

Write desired temperature

```taphome
IF(GETBIT(MODBUSR(A, 0, UInt16),1)=0, MODBUSW(H, 52, UInt16, Se * 10),MODBUSW(H, 53, UInt16, Se * 10));
```

Read humidity

```taphome
MODBUSR(A, 3, Uint16) / 100
```

Service Attributes

Setpoint temperature supervision enabled

```taphome
Switch(GETBIT(MODBUSR(H, 50, Uint16),13), 0, "Disabled", 1, "Enabled","Unknown");
```

Minimum setpoint cool

```taphome
MODBUSR(H, 54, Uint16)/10;
```

Maximun setpoint cool

```taphome
MODBUSR(H, 55, Uint16)/10;
```

Minimun setpoint heat

```taphome
MODBUSR(H, 56, Uint16)/10;
```

Maximun setpoint heat

```taphome
MODBUSR(H, 57, Uint16)/10;
```

Fan Speed Multi-value Switch Read and write

Fan speed selector — Off, Very low, Low, Medium, High; supports step control or modulating percentage

Register: A:1 → H:58 UInt16 numeric

Values / States: Off · Very low · Low · Medium · High

Read switch state

```taphome
MODBUSR(A,1, UInt16)
```

Write switch state

```taphome
MODBUSW(H, 58, UInt16, Mu)
```

Service Attributes

Modulating fan mode

```taphome
Switch(MODBUSR(H, 60, Uint16), 0, "Fan off", 1, "Manually forced fan", 2, "Automatic fan operation", "Unknown");
```

Fan spees supervision enabled

```taphome
Switch(GETBIT(MODBUSR(H, 50, Uint16),15), 0, "Disabled", 1, "Enabled","Unknown");
```

**Connection:** Modbus RTU • 9600 baud• 8N2 • Slave ID: $\[SlaveId]

Possible improvements (10)

- A:5 P00: System Configuration — System configuration code (001–038) — defines pipe count, valve type, speeds, S/W logic
- A:7 Active Setpoint — Currently active temperature setpoint × 10 (°C) — useful for monitoring actual target vs user setpoint
- A:9 LCD Version — Controller firmware version — useful as service attribute
- A:15 Analog Output 1 — Current value of analog output 1 (%) — valve modulation or fan modulation depending on P14
- A:16 Analog Output 2 — Current value of analog output 2 (%) — fan modulation or hot water valve depending on P14
- H:51 Hourly Programming — Timer-programmed operating mode — 0=disabled, 1=ON/OFF schedule, 2=SETPOINT schedule
- H:59 Economy Correction — Economy mode setpoint correction × 10 (°C) — adjusts setpoint when Eco mode is active via H:50 bit 3
- A:0 (bit 5) Keypad Lock Status — Read-only status of keypad lock; write via H:50 bit 5
- A:0 (bit 3) Economy Mode Status — Whether economy mode is active; controlled via H:50 bit 3 (requires En.ECO bit 11)
- A:0 (bit 12) Dehumidification Status — Whether dehumidification is currently active

## Import parameters

Enter these values when you import the XML.

| Asked in the app | Default       |
|------------------|---------------|
| Slave ID         | `1`           |
| IP address       | `192.168.1.0` |

## Sources

- FWEC3 Advanced Plus — Installation and Operation Manual
  
  [daikin.kh.ua](https://daikin.kh.ua/wp-content/uploads/2021/IM-OM_FWEC3A_EN_tcm135-266991.pdf) 2026-03-29
  
  [PDF](https://taphome.com/compatibility/devices/daikin-fwec3/manufacturer/fwec3a-manual.pdf)

Manufacturer documents are © their respective owners. They are provided as published by the manufacturer, for reference only.

## 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/)