Hello KinCony team,

I am using a KC868-A16 (original ESP32 v1.6, not A16v3) with KCS firmware v2.2.20 (build date Apr 2 2026), integrated into Home Assistant via MQTT (Mosquitto broker). Everything works: I control the outputs with {"outputN":{"value":true/false}} on KC868_A16/<serial>/SET and I read inputs and outputs from KC868_A16/<serial>/STATE.

I would like to use all the features of the board, so I have a few questions:

1. Complete MQTT documentation
Could you please send me the latest and complete MQTT protocol document for KCS v2.2.20? I need the full list of topics, commands and payload fields, including outputs, digital inputs, HT1–HT3 inputs, analog inputs (ADC), temperature/humidity sensors, RF 433 MHz, and any other parameter available via MQTT.

2. Availability / Last Will (LWT)
Does KCS v2 publish an availability or Last Will message (online/offline) when the board connects or disconnects from the broker? If yes, which topic and payload does it use? If not, is it possible to add it in a future firmware version?

3. Home Assistant MQTT Auto Discovery
Is Home Assistant MQTT auto discovery supported in KCS v2 for the KC868-A16, or only in KCS v3? If it is supported, where can I enable it?

4. Pulse command with duration
At the moment I use the "delay" output type in the web interface to create a pulse. Is there an MQTT command to send a pulse with a duration specified in the payload (for example "turn on output 5 for 300 ms"), so that the timing can be chosen per command?

5. Other commands
- Is there a command to request the full current state (refresh/query)?
- Is there a toggle command for outputs?
- Can the board publish its state periodically (heartbeat), and is the interval configurable?
- Are STATE messages published with the retain flag, and can this be configured?

6. Values for sensors not connected
I see "temperature":-100 and "humidity":-100 for sensors that are not connected. Can you confirm that -100 always means "no sensor"?

7. Firmware
Is v2.2.20 the latest KCS v2 firmware for the KC868-A16? Is a changelog available?

If you also have HTTP or TCP protocol documents for KCS v2, I would appreciate them too.

• Connect the two wires from the same end of the sensing element to the two “+” terminals, one wire to each terminal.
  
• Connect the remaining wire to the “−” terminal.
  
• No external power supply is required for the sensor.
  

   
Connect multiple Modbus RTU devices to a single RS485 port, with KCS v3 acting as the master to poll and read each device.
The example includes a temperature sensor, a humidity sensor, and an energy meter, with Modbus addresses 1, 2, and 3, respectively. The diagram shows the A/B bus, termination resistors at both ends, and requirements such as unique device addresses and matching serial communication settings.

• Controller TXD → G1 RXD
  
• Controller RXD ← G1 TXD
  
• GND → Common ground
  
• G1 requires an external power supply, a SIM card, and a 4G antenna.
  

• D0 → GPIO A
  
• D1 → GPIO B
  
• GND → GND
  

• 12 V LED driver → 12 V LED strip
  
• 24 V LED driver → 24 V LED strip
  
• AC dimmer with a 0–10 V input → Dimmable AC 220 V lamp
  

• 0–5 V / 0–10 V: Connect the sensor OUT to AI1. Connect the sensor and controller to a common GND.
  
• 2-wire 4–20 mA: Power supply positive → Transmitter +; Transmitter − → AI1; Controller GND → Power supply negative.
  

• DI1 connected to GND: TRUE
  
• DI1 disconnected from GND: FALSE
  

• COM connected to GND: The switch connects +12/24 V to DI1.
  
• COM connected to +12/24 V: The switch connects GND to DI1.