{
  "$schema": "https://raw.githubusercontent.com/nobrega8/mbmap-library/main/schema/mbmap-2.schema.json",
  "mbmap": 2,
  "vendor": "LinkedGo",
  "model": "ST802-B",
  "models": [
    "ST802-B",
    "ST802",
    "LinkedGo ST802-B"
  ],
  "vendor_website": "linkedgo.com",
  "description": "Smart HVAC thermostat (fan coil, underfloor heating, ventilation) with RS-485 (Modbus RTU), sold by Shelly",
  "revision": 1,
  "revised": "2026-10-18",
  "source": "LinkedGo, \"ST802 Youth Smart Thermostat technical instruction\", section 11, RS485 Modbus protocol of LinkedGo 3.0",
  "sources": [
    {
      "title": "ST802 Youth Smart Thermostat technical instruction",
      "url": "https://storage.googleapis.com/mauser-public-images/prod_description_document/2025/282/ca065a98d3074f9a4833a0add36f3fcd_cf31db8df7d388aae17e00dc60a3be462c3f40b6.pdf",
      "note": "manufacturer document for the ST802; sections 9 to 12"
    },
    {
      "title": "Shelly: Smart HVAC Thermostat (ST802-B)",
      "url": "https://www.shelly.com/blogs/documentation/smart-hvac-thermostat"
    }
  ],
  "notes": [
    "Function codes: FC03 reads, FC06 and FC16 write. Addresses are the hexadecimal registers of the manual; the registers of the status group (0x2101 and following) are read-only.",
    "The manual describes the ST802. Shelly lists RS-485/Modbus control for the ST802-B (the Shelly edition) but publishes no register table, so this map assumes the same LinkedGo 3.0 protocol; it has not been checked on an ST802-B.",
    "Two RS-485 ports (A1/B1 and A2/B2). In the factory settings port 1 is a master (P00 = 1) and port 2 a slave (P05 = 0); set the port that connects to your controller to slave, protocol LinkedGo 3.0, baud rate 4800 or 9600 (default 9600), slave ID 1 to 255 (default 1) from the display menu or these registers.",
    "The manual does not state the parity or stop bits; 8 data bits, no parity and 1 stop bit are assumed.",
    "Temperatures and humidity are in tenths: 10 means 1 °C or 1 %."
  ],
  "protocol": "rtu",
  "unit_id": 1,
  "baudrate": 9600,
  "parity": "N",
  "databits": 8,
  "stopbits": 1,
  "byte_order": "big",
  "word_order": "big",
  "address_base": 0,
  "x_status": "official",
  "registers": [
    {
      "name": "On/off",
      "group": "Control",
      "area": "holding",
      "address": 4097,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Off",
        "1": "On"
      },
      "description": "H00"
    },
    {
      "name": "Thermostat function",
      "group": "Control",
      "area": "holding",
      "address": 4099,
      "type": "uint16",
      "access": "RW",
      "description": "H02: 0, 1, 2, 3 or 17 (fan coil and floor heating combination; see the manual)",
      "write_min": 0,
      "write_max": 17
    },
    {
      "name": "Mode",
      "group": "Control",
      "area": "holding",
      "address": 4100,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Cooling",
        "3": "Dry",
        "4": "Heating",
        "5": "Floor heating",
        "7": "Ventilation"
      },
      "description": "H03"
    },
    {
      "name": "Heating and cooling function",
      "group": "Control",
      "area": "holding",
      "address": 4102,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Heating and cooling",
        "1": "Only cooling",
        "2": "Only heating"
      },
      "description": "H05"
    },
    {
      "name": "Fan speed",
      "group": "Control",
      "area": "holding",
      "address": 4103,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Auto",
        "1": "Low",
        "2": "Medium",
        "3": "High",
        "4": "Fourth speed",
        "5": "Fifth speed"
      },
      "description": "H06. AC fans: 0 to 3; DC fans: 0 to 5"
    },
    {
      "name": "Set point",
      "group": "Control",
      "area": "holding",
      "address": 4104,
      "type": "uint16",
      "unit": "°C",
      "access": "RW",
      "scale": 0.1,
      "description": "H07. Between the minimum and maximum set point; steps of 0.5 °C"
    },
    {
      "name": "Humidity set point",
      "group": "Control",
      "area": "holding",
      "address": 4105,
      "type": "uint16",
      "unit": "%",
      "access": "RW",
      "scale": 0.1,
      "write_min": 40,
      "write_max": 75,
      "description": "H08"
    },
    {
      "name": "Minimum set point",
      "group": "Settings",
      "area": "holding",
      "address": 4120,
      "type": "uint16",
      "unit": "°C",
      "access": "RW",
      "scale": 0.1,
      "write_min": 5,
      "write_max": 50,
      "description": "H23, up to the maximum set point"
    },
    {
      "name": "Maximum set point",
      "group": "Settings",
      "area": "holding",
      "address": 4121,
      "type": "uint16",
      "unit": "°C",
      "access": "RW",
      "scale": 0.1,
      "description": "H24, from the minimum set point to 50 °C"
    },
    {
      "name": "DC fan lowest speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4176,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F02"
    },
    {
      "name": "DC fan highest speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4177,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F03"
    },
    {
      "name": "DC fan 1st speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4179,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F05"
    },
    {
      "name": "DC fan 2nd speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4180,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F06"
    },
    {
      "name": "DC fan 3rd speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4181,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F07"
    },
    {
      "name": "DC fan 4th speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4182,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F08"
    },
    {
      "name": "DC fan 5th speed voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4183,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F09"
    },
    {
      "name": "DC fan minimum voltage at start",
      "group": "DC fan",
      "area": "holding",
      "address": 4184,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F10"
    },
    {
      "name": "DC fan initial start voltage",
      "group": "DC fan",
      "area": "holding",
      "address": 4185,
      "type": "uint16",
      "unit": "V",
      "access": "RW",
      "scale": 0.01,
      "description": "F11"
    },
    {
      "name": "DC fan start time",
      "group": "DC fan",
      "area": "holding",
      "address": 4186,
      "type": "uint16",
      "unit": "s",
      "access": "RW",
      "write_min": 2,
      "write_max": 180,
      "description": "F12"
    },
    {
      "name": "RS485-1 role",
      "group": "Communication",
      "area": "holding",
      "address": 4238,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Slave",
        "1": "Master"
      },
      "description": "P00"
    },
    {
      "name": "RS485-1 baud rate",
      "group": "Communication",
      "area": "holding",
      "address": 4239,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "2": "4800",
        "3": "9600"
      },
      "description": "P01"
    },
    {
      "name": "RS485-1 protocol",
      "group": "Communication",
      "area": "holding",
      "address": 4240,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "LinkedGo 3.0",
        "3": "DC fan"
      },
      "description": "P02"
    },
    {
      "name": "RS485-1 slave ID",
      "group": "Communication",
      "area": "holding",
      "address": 4241,
      "type": "uint16",
      "access": "RW",
      "write_min": 1,
      "write_max": 255,
      "description": "P03"
    },
    {
      "name": "RS485-2 role",
      "group": "Communication",
      "area": "holding",
      "address": 4242,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "0": "Slave",
        "1": "Master"
      },
      "description": "P05"
    },
    {
      "name": "RS485-2 baud rate",
      "group": "Communication",
      "area": "holding",
      "address": 4243,
      "type": "uint16",
      "access": "RW",
      "enum": {
        "2": "4800",
        "3": "9600"
      },
      "description": "P06"
    },
    {
      "name": "RS485-2 protocol",
      "group": "Communication",
      "area": "holding",
      "address": 4244,
      "type": "uint16",
      "access": "RW",
      "description": "P07: 11 = LinkedGo 3.0"
    },
    {
      "name": "RS485-2 slave ID",
      "group": "Communication",
      "area": "holding",
      "address": 4246,
      "type": "uint16",
      "access": "RW",
      "write_min": 1,
      "write_max": 255,
      "description": "P08"
    },
    {
      "name": "Room temperature",
      "group": "Measurements",
      "area": "holding",
      "address": 8449,
      "type": "uint16",
      "unit": "°C",
      "access": "R",
      "scale": 0.1,
      "description": "O00"
    },
    {
      "name": "Room humidity",
      "group": "Measurements",
      "area": "holding",
      "address": 8450,
      "type": "uint16",
      "unit": "%",
      "access": "R",
      "scale": 0.1,
      "description": "O01"
    },
    {
      "name": "Temperature O02",
      "group": "Measurements",
      "area": "holding",
      "address": 8451,
      "type": "uint16",
      "unit": "°C",
      "access": "R",
      "scale": 0.1,
      "description": "O02; the manual does not name this value"
    },
    {
      "name": "High speed relay",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 0,
      "access": "R",
      "description": "1 = relay closed"
    },
    {
      "name": "Medium speed relay",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 1,
      "access": "R"
    },
    {
      "name": "Low speed relay",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 2,
      "access": "R"
    },
    {
      "name": "Fan coil valve",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 3,
      "access": "R"
    },
    {
      "name": "Floor heating valve",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 4,
      "access": "R"
    },
    {
      "name": "Dry contact output",
      "group": "Status",
      "area": "holding",
      "address": 8464,
      "type": "bool",
      "bit": 5,
      "access": "R"
    },
    {
      "name": "Room sensor failure",
      "group": "Status",
      "area": "holding",
      "address": 8474,
      "type": "bool",
      "bit": 0,
      "access": "R",
      "description": "Alarm E03"
    }
  ]
}