{
  "$schema": "https://raw.githubusercontent.com/nobrega8/mbmap-library/main/schema/mbmap-2.schema.json",
  "mbmap": 2,
  "vendor": "XY",
  "model": "XY-MD02",
  "models": [
    "XY-MD02"
  ],
  "description": "RS485 temperature and humidity transmitter with an SHT20 sensor, Modbus RTU",
  "revision": 2,
  "revised": "2026-11-08",
  "source": "XY-MD02 Modbus RTU RS485 SHT20 Temperature Humidity Transmitter manual",
  "sources": [
    {
      "title": "XY-MD02 Modbus RTU RS485 SHT20 Temperature Humidity Transmitter manual",
      "note": "Modbus protocol tables and examples"
    },
    {
      "title": "Test report on an XY-MD02",
      "date": "2026-11-08",
      "url": "https://github.com/nobrega8/mbmap-library/issues/161",
      "note": "baud rate encoding, correction scale and stop bits"
    }
  ],
  "notes": [
    "Function codes 0x03, 0x04, 0x06 and 0x10. Temperature and humidity are input registers (FC04); the settings are holding registers (FC03 read, FC06 or FC10 write).",
    "Addresses are the ones in the manual's frames: temperature is read from address 0x0001 (frame 01 04 00 01 00 01).",
    "The baud rate register holds the rate itself in bit/s (9600 reads 9600), as in the manual's write example; the 0/1/2 codes in the manual's register table are wrong.",
    "The temperature correction is in tenths of a degree: writing 10 raised the reading by about 1 °C. The humidity correction was not tested and is taken to work the same way. The manual's range of -10 to 10 is therefore -100 to 100 on the wire.",
    "Factory defaults: 9600 bit/s, 8N1, address 1. The device uses 1 stop bit, but it also answers a master set to 2.",
    "A new address or baud rate applies only after the device is powered off and on again.",
    "Tested on an XY-MD02, firmware not shown, November 2026: temperature (including -1.8 °C, read as 0xFFEE), humidity, the address and baud rate registers, the serial settings and the temperature correction. The humidity correction was not tested."
  ],
  "protocol": "rtu",
  "unit_id": 1,
  "baudrate": 9600,
  "parity": "N",
  "databits": 8,
  "stopbits": 1,
  "address_base": 0,
  "x_status": "verified",
  "registers": [
    {"name": "Temperature", "group": "Measurement", "area": "input", "address": 1, "type": "int16", "scale": 0.1, "unit": "°C", "access": "R", "description": "Signed value in tenths of a degree (0x0131 is 30.5 °C, 0xFF33 is -20.5 °C)"},
    {"name": "Humidity", "group": "Measurement", "area": "input", "address": 2, "type": "uint16", "scale": 0.1, "unit": "%RH", "access": "R", "description": "Relative humidity in tenths of a percent (0x0222 is 54.6 %RH)"},
    {"name": "Device address", "group": "Configuration", "area": "holding", "address": 257, "type": "uint16", "access": "RW", "write_min": 1, "write_max": 247, "description": "Modbus slave address, default 1. Applies after a power cycle"},
    {"name": "Baud rate", "group": "Configuration", "area": "holding", "address": 258, "type": "uint16", "unit": "bit/s", "access": "RW", "description": "The rate itself, for example 9600 or 19200. Applies after a power cycle"},
    {"name": "Temperature correction", "group": "Configuration", "area": "holding", "address": 259, "type": "int16", "scale": 0.1, "unit": "°C", "access": "RW", "write_min": -10, "write_max": 10, "description": "Added to the measured temperature, in steps of 0.1 °C"},
    {"name": "Humidity correction", "group": "Configuration", "area": "holding", "address": 260, "type": "int16", "scale": 0.1, "unit": "%RH", "access": "RW", "write_min": -10, "write_max": 10, "description": "Added to the measured humidity, in steps of 0.1 %RH"}
  ]
}