This is a Home Assistant integration for the Nilan CTS600 HVAC control system, controlling e.g. the Nilan VPL-15 ventilation unit. This integration, via a serial RS485/Modbus adapter, is to be connected to the ventilation unit and replaces the physical control panel.
Currently, this integration implements the Climate interface for Home Assistant. This means that you can set the ventilation unit's mode (auto, heat, cool, or off) and its target temperature. You can also set the fan speed (1, 2, 3, or 4). Finally, the thermometer in the physical control panel (Nilan sensor T15) is replaced with any HA entity, typically a temperature sensor. Also, there are button entities corresponding to the physical buttons, and separate sensor entities for the text display and various temperatures and fan speed.
The Nilan VPL-15 ventilation unit (and similar units from Nilan) have been delivered with a range of control systems over the years, starting I believe with simple analog controls back in the day, until todays modern CTS602 or CTS700-based control systems that support LAN interfacing, mobile apps and whatnot.
This integration is specifically for units controlled via the CTS600 interface. Historically this is an intermediate technology, and obsolete now since a number of years. The CTS600 is a digital system and protocol, but not really designed to be interfaced or integrated with other systems.
There exists a different integration in HACS for CTS602-based systems, named Nilan.
This integration is created for my Nilan VPL-15 ventilation unit controlled by CTS600. There are other Nilan ventilation units provided with the CTS600 controller. These systems may or may not work as is. If you have such a non-VPL-15 system, I'd be interested in making this integration work, so please test and open an Github issue for this purpose.
The following is a list of Nilan ventilation units other than the VPL-15 that I believe have been delivered with the CTS600 controller:
- Comfort-450
- Comfort-600
- Comfort-300
- VPL-28
- VP-18 M2
- VGU-250
The Comfort-300 has reportedly also been tested.
An adapter is required to interface the CTS600 to the PC running Home Assistant. I am using a USB serial RS485 (modbus) adapter. These come in many shapes and colours. I reccommend the one that is black with green screw terminals and a USB pigtail. Link to Aliexpress. I'd advise against the blue translucent ones.
The Nilan VPL-15 (and presumably other) unit connects to the physical control panel via 4 wires. Two wires provide 12V power, and the remaining two are the RS485 A and B communication wires.
Only the two A and B communication wires must be connected to the USB adapter. These will be labeled on the adapter. Do not connect the power wires to the adapter, as this will likely destroy your adapter, and possibly also your PC and/or ventilation unit!
The image below identifies the wires on the side of the original control panel.
This integration supports UI configuration and manual configuration in configuration.yaml.
Configuration via the UI is hopefully self-explanatory. See also documentation for YAML configuration below.
This is an example configuration for configuration.yaml:
climate:
platform: nilan_cts600
name: LoftCTS600
retries: 3
sensor_T15: input_number.stuetemp
port: /dev/ttyUSB0
These are the configuration entries:
name: Any name you choose to identify the ventilation unit.retries: The number of times to retry a CTS600 request before failing.sensor_T15: Names the entity that provides the value for the room temperature, substituting the temperature sensor in the original control panel.port: The device node corresponding to your RS485 adapter. If you have no other USB serial adapters installed, this will be/dev/ttyUSB0.
This integration emulates the physical control panel. You can (currently) not use the physical control panel while using this integration.
The CTS600 appears to use a pseudo-modbus protocol atop of RS485, where the control panel is the master and the ventilation unit (controller) is the slave. However, the communications is not based on standard modbus registers. Rather, the CTS600 employs some "custom" modbus function codes, such that the basic communications structure (after initialization) is like this:
- The panel sends a custom "request" that informs the controller of the state of the six buttons.
- The controller "responds" with a somewhat random status update: the text for the display, or the state of the status LED.
- Repeat forever, several times every second.
The CTS600 will accept and respond to standard modbus register commands, but I have not found a way to control or query the ventilation controller this way.
Because standard modbus registers don't work, the integration is reduced to emulating the physical control panel. That is, it emulates pressing the buttons and parsing the display text, just as a human would do. This is rather inefficient, but seems to work. These are some consequences of this mode of operation:
- In order to parse the text display, during initialization the integration will switch the controller interface language to english.
- The precision of temperature values is limited to that displayed on the physical control panel, i.e. mostly whole integers.
- The integration must make some assumptions about the nature of the controller menus. These might change between controller versions and ventilation unit models. Consequently, it's difficult to predict interoperability between versions and models, but it should be easy to adapt.
The CTS600 protocol uses some unknown internal 16-bit representation
for the T15 room temperature sensor value. The precision of this
representation is a bit less than 0.1°C. Also, it appears to be
slightly non-linear with respect to the celsius
representation. Currently a linear approximation is used. Therefore,
the reported T15 value will deviate slightly from whatever input value
you provide (via the sensor_t15 configuration entry). The error will
increase towards the extremes, especially below 10°C.
These are a few pieces of information about the CTS600 I have come across that is not directly relevant to the HA integration, but some might still find useful.
The CTS600 provides 12 volts power to the control panel. However, the control panel will operate just fine on 5 volts, and so it can be hooked up directly to your USB RS486 adapter which typically provides 5 volts. (This would be e.g. for probing the control panel to figure out its operation.)
If you find that your (physical) control panel is unable to communicate with the ventilation unit, and you are certain the wiring is correct: The most likely culprit is the RS485 driver chip that sits on either end of the communication. The chip is an ADM483 8-pin SMD, which is a bit tricky but not impossible to replace for someone with a bit of experience with a soldering iron. I've had to replace both of mine. For the CTS600 controller in the ventilation unit you'll want to remove the PCB from the unit, which is not difficult if you just take note of where every plug should go back in. The ADM483 is located right next to the communications connector on the PCB, on both ends.