# Modbus page

### **Modbus**

Modbus devices are connected to terminals **15 and 16**. 

***

### **Modbus Settings for RFTC-3**

RFTC-3 operates as a **Modbus Master** for controlling FCU or heating units. The Modbus settings allow configuration of communication parameters and the list of connected devices.

#### **Modbus Setting**

This section allows you to configure the basic communication parameters according to the requirements of the connected unit:

* **Baudrate** – Transmission speed
* **Parity** – Parity check
* **Stop Bit** – Number of stop bits After setting the values, confirm the changes by clicking **Change**.

***

#### **List of Modbus Devices**

This section lets you add or remove Modbus devices. Options:

* **Add device** – Add a new device
* **Delete device** – Remove an existing device When adding a device, enter the following:
* **Slave ID** – The device identifier in the Modbus network (found in the device's documentation)
* **Description** – A user-friendly name for easy identification **Registers for control:**
* **ON/OFF** – Register to turn the device on or off
* **Set Temperature** – Register for setting the desired temperature (with appropriate multiplier)
* **Fan Speed** – Register for controlling fan speed (with specific regulation sequence)
* **Mode** – Register for changing between heating/cooling modes (with appropriate switching logic)
* **Swing** – Register to control louver movement

> **Note:** Not all fields are mandatory. They can be activated using the parameter `activation=ON`. Only one unit can be configured and connected this way. Refer to the documentation of the connected devices for all required setup details.

***

### **Control**

* **ON/OFF** – Can be controlled from the RFTC-3 display via the ON/OFF button
* **Set Temperature** – RFTC-3 sends the desired temperature to the unit
* **Fan Speed** – RFTC-3 sends the desired fan speed
* **Mode** – Controlled via the "Mode" button on the display
* **Swing** – Remains active if `activation=ON`

***

###