Nilan VP18
Controls Nilan VP18 heat recovery unit via CTS 602 over Modbus RTU.
This template connects a Nilan VP18 heat recovery unit with CTS 602 control to ModbusCloud over Modbus RTU. It reads temperatures, humidity, fan speeds, compressor status, and alarms. It also allows control of ventilation mode, fan speed, and temperature setpoints.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 32, read and write
- Brand
- Nilan
- Key readings
- Intake/Evap/Cond/Inlet temperatures · Room and controller temperatures · Relative humidity · Exhaust and inlet fan speed · Compressor and water heat status · Alarm IDs
- Available commands
- Ventilation mode and state · Ventilation speed setpoint · Temperature setpoint · Hot water temperature setpoints
- Compatible models
- Nilan VP18
- Last updated
Registers (32)
31 read, 8 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Control.RunAct | Read | ||||
| Control.ModeAct | Read and write | ||||
| Control.SecInState | s | Read and write | |||
| Input.T1_Intake | °C | Read | |||
| Input.T6_Evap | °C | Read | |||
| Input.T5_Cond | °C | Read | |||
| Input.T10_Extern | °C | Read | |||
| Input.T7_Inlet | °C | Read | |||
| AirQual.RH | % | Read | |||
| Alarm.List_1_ID | Read | ||||
| Alarm.List_2_ID | Read | ||||
| Alarm.List_3_ID | Read | ||||
| Input.T11_Top | °C | Read | |||
| Input.T12_Bottom | °C | Read | |||
| Input.Boil | Read | ||||
| Control.State | Read and write | ||||
| Input.T0_Controller | °C | Read | |||
| Input.T15_Room | °C | Read | |||
| AirFlow.VentSet | Read and write | ||||
| Output.ExhaustSpeed | % | Read | |||
| Output.InletSpeed | % | Read | |||
| Control.TempSet | °C | Read and write | |||
| Output.Compressor | Read | ||||
| Output.WaterHeat | Read | ||||
| HotWater.TempSet_T11 | °C | Read and write | |||
| HotWater.TempSet_T12 | °C | Read and write | |||
| AirTemp.TempMaxSum | °C | Read | |||
| AirTemp.TempMinSum | °C | Read | |||
| AirTemp.TempMaxWin | °C | Read | |||
| AirTemp.TempMinWin | °C | Read | |||
| AirTemp.TempSummer | °C | Read | |||
| Alarm.Reset | Write |
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Use cases
- Monitor intake, condenser, and room temperatures on a live dashboard to verify heat recovery performance.
- Adjust ventilation speed and mode remotely when occupancy patterns change at a customer site.
- Create an alert when an alarm ID is active so you can respond to faults before the end user notices.
- Log hot water temperature setpoints and actual values over time to optimize energy consumption.
- Track compressor run status and fan speeds to identify maintenance needs before components fail.
Installation
Wire the Modbus RTU bus (A and B terminals) from the Nilan CTS 602 controller to the RS-485 port on your ModbusCloud Gateway.
Set the Modbus slave address on the CTS 602 controller and ensure it does not conflict with other devices on the bus.
Configure the gateway serial port to 19200 baud, 8 data bits, odd parity (1), and 1 stop bit to match the CTS 602 settings.
Import the Nilan VP18 template from the ModbusCloud template library into your project.
Verify communication by checking that live temperature and fan speed readings appear on the ModbusCloud dashboard.
Test a writable parameter such as the ventilation speed setpoint to confirm bidirectional communication is working.
Things to watch for
Why do I get incorrect temperature readings from the VP18?
Temperature values on the CTS 602 are stored as int16 integers and often require a scale factor (for example, dividing by 10 or 100). Check the Nilan Modbus specification for the correct scaling per register.
Why do some registers return wrong data or no data at all?
The CTS 602 uses overlapping register addresses for input and output registers. You must use the correct Modbus function code for each register. For example, reading an input register with a holding register function code will return incorrect values.
What baud rate and parity settings should I use?
The Nilan VP18 with CTS 602 requires 19200 baud and odd parity. Make sure both the gateway and the CTS 602 are set identically, otherwise communication will fail.
Can I use this template with other Nilan models that have a CTS 602 controller?
This template is configured specifically for the Nilan VP18. Other Nilan models with CTS 602 may share many registers, but differences can exist. Verify against the Modbus specification for your specific model before using it.
More Nilan templates
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