An installation guide for the MQTT API bindings is part of their general description.
All published payloads to and from the MQTT bindings are in JSON format.
If an error occures, the bindings publish a JSON object containing the error message as member
It is published on the corresponding response topic:
Returns the UID, the UID where the Brick is connected to, the position, the hardware and firmware version as well as the device identifier.
The position is the position in the stack from '0' (bottom) to '8' (top).
The device identifier numbers can be found here. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.
The display name contains the ESP32's name in a human readable form.