A company from Belgium used an Unipi Axon controller as a communication gateway for an HVAC remote management project
The ESIV company from Belgium uses Unipi Axon PLCs as controllers for HVAC control projects offered to third-party clients. Among these clients is a certain HVAC system distributor which contacted the ESIV company with a requirement of HVAC installation remote management. For this project the Unipi Axon S205 compact controller was chosen, featuring eight digital inputs and eight relay outputs.
In the installation, the controller communicates with an HVAC unit through the RS485 serial interface (Modbus RTU protocol). A pair of external relays are used for detecting external alerts is connected to digital inputs, while one of the relay outputs drives an external relay designed to instantly cut the power to the HVAC unit in case of emergency. The controller’s Ethernet port is then utilized for communication with an external 4G modem which sends notifications and alerts via the 4G mobile network.
As the software solution, the Node-RED software is used for sending alerts and notifications through the MQTT protocol. Additionally, the project utilizes the OpenVPN for maintaining a secure VPN connection to manage the HVAC unit remotely.