3. MQTT Subscriber implementation

MQTT stands for MQ Telemetry Transport. It is a publish/subscribe lightweight messaging protocol, designed for constrained devices and low-bandwidth, high-latency or unreliable networks.

The app can be setup as a MQTT subscriber, this allows you to view the classic data anywhere on the internet without having to setup port forwarding in your router.

A Raspberry Pi or ESP32 Dev board is required, as detailed in the ClassicMQTT project, to be setup as a publisher. This 'publisher' is on your local network that reads the data from the classic using the Modbus protocol, it will publish the data to a MQTT broker which normally resides in the 'cloud'. A number of services exist both free and paid such as DIoTY and Amazon IOT core.

The Android device that is setup as a subsciber will consume the data from the MQTT broker and display the information as it does on the regular Version 2.x of the Android App. Currently, the Day, Hour logs and calendar are not supported on the subscriber.

Please refer to the ClassicMQTT wiki for more information.