Nordic Flexit
Controls and monitors Nordic Flexit ventilation system units via Modbus RTU
This template connects Nordic Flexit ventilation system units via Modbus RTU. It reads air temperatures, alarm status, filter hours, and operating mode. It also provides control over setpoints, operating mode, fireplace ventilation, and rapid ventilation triggers.
- Protocol
- Modbus RTU
- Connection
- RS485, 9600 baud
- Registers
- 13, read and write
- Brand
- Nordic
- Key readings
- Outside Air Temp · Supply Air Temp · Extract Air Temp · Exhaust Air Temp · Alarm Indication · Operating Time Filter
- Available commands
- Room Operating Mode · Setpoint Temp Home / Away · Trigger Fireplace / Rapid Vent · Comfort Button
- Compatible models
- Nordic Flexit · Nordic Flexit S4
- Last updated
Registers (13)
10 read, 6 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Room Operating Mode | Read and write | ||||
| Outside Air Temp | °C | Read | |||
| Supply Air Temp | °C | Read | |||
| Alarm Indication | Read | ||||
| Extract Air Temp | °C | Read | |||
| Exhaust Air Temp | °C | Read | |||
| Setpoint Temp Away | °C | Read and write | |||
| Setpoint Temp Home | °C | Read and write | |||
| Operating Time Filter Replacement | hod. | Read | |||
| Operating Time Filter | hod. | Read | |||
| Trigger Fireplace | Write | ||||
| Trigger Rapid Vent | Write | ||||
| Comfort button | Write |
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Use cases
- Monitor supply and extract air temperatures on a live dashboard to verify heat recovery performance.
- Create an alert when the alarm indication register signals a fault on the Nordic Flexit unit.
- Track filter operating hours remotely and notify the end user when a filter replacement is due.
- Adjust home and away temperature setpoints remotely without visiting the installation site.
- Trigger fireplace ventilation mode from the cloud when coordinating with a wood stove installation.
- Log outside air temperature alongside supply air temperature to evaluate heat recovery efficiency over time.
Installation
Connect the Modbus RTU wiring (A and B terminals) from the Nordic Flexit unit to the RS485 port on your ModbusCloud Gateway.
Verify that the Nordic Flexit is configured with slave address 1, baud rate 9600, 8 data bits, even parity, and 1 stop bit.
Match the same serial port settings (9600, 8E1) on the ModbusCloud gateway RS485 port configuration.
Import the Nordic Flexit template from the ModbusCloud template library and assign it to the correct gateway and port.
Set the Comfort Button register (address 2040) to 1 in the ModbusCloud interface to enable write access to all control registers.
Confirm live data is appearing on the dashboard by checking that temperature values and filter hours are reading correctly.
Things to watch for
Why are all write commands to the Nordic Flexit being ignored?
All write registers only function when the Comfort Button at Modbus address 2040 is set to 1. Enable this register first before attempting any control operations.
Temperature readings show unrealistic values. What is wrong?
Temperature and filter hour registers use float32 format, which spans two consecutive 16-bit registers. Ensure your gateway is configured for the correct byte order and word order (typically big-endian) to decode float32 values properly.
The gateway cannot communicate with the Nordic Flexit unit. What should I check?
Verify that the serial settings match exactly: baud rate 9600, 8 data bits, even parity, 1 stop bit, and slave address 1. Also check that the A and B wires are not swapped and that a termination resistor is present if the cable run is long.
Can I use this template with the Nordic Flexit S4 model?
Yes. This template is compatible with both the standard Nordic Flexit and the Nordic Flexit S4. The register map and communication settings are the same.
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