MBMap Registry
  1. Devices
  2. LinkedGo
  3. ST802-B

LinkedGo ST802-B Modbus register map

Also covers LinkedGo ST802-B

Smart HVAC thermostat (fan coil, underfloor heating, ventilation) with RS-485 (Modbus RTU), sold by Shelly

  • Official
  • 37 registers
  • Modbus RTU
  • Revision 1 · 2026-10-18

Official: Written from the manufacturer's documentation, but not tested on a device yet. Check the map against the manufacturer's documentation before you write to a live device. Tested it? Report a test.

Download .mbmap.json Raw JSON View on GitHub Suggest a correction Report a problem

Communication

Protocol
Modbus RTU
Unit ID
1
Serial
9600 8N1 · 9600 baud, 8 data bits, none parity, 1 stop bit
Byte / word order
ABCD · bytes big-endian, words high first
Addresses
0-based

Connection values are defaults: the device may be configured differently.

Map

Registers
37 holding registers
Groups
6
Revision
1 · 2026-10-18
Added
()
File
maps/linkedgo/st802-b.mbmap.json · 11 KB · history
SHA-256
63fe3a23c3a2442fc93e0575c2d9151341a2446a39908c94dd287dd5b1adc802
Manufacturer
linkedgo.com

Sources and notes

Source: LinkedGo, "ST802 Youth Smart Thermostat technical instruction", section 11, RS485 Modbus protocol of LinkedGo 3.0

  • 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 %.
AreaAddressNameTypeAccessUnitScaleDescription
HR 4097 uint16 RW H00
HR 4099 uint16 RW H02: 0, 1, 2, 3 or 17 (fan coil and floor heating combination; see the manual)
HR 4100 uint16 RW H03
HR 4102 uint16 RW H05
HR 4103 uint16 RW H06. AC fans: 0 to 3; DC fans: 0 to 5
HR 4104 uint16 RW °C ×0.1 H07. Between the minimum and maximum set point; steps of 0.5 °C
HR 4105 uint16 RW % ×0.1 H08
HR 4120 uint16 RW °C ×0.1 H23, up to the maximum set point
HR 4121 uint16 RW °C ×0.1 H24, from the minimum set point to 50 °C
HR 4176 uint16 RW V ×0.01 F02
HR 4177 uint16 RW V ×0.01 F03
HR 4179 uint16 RW V ×0.01 F05
HR 4180 uint16 RW V ×0.01 F06
HR 4181 uint16 RW V ×0.01 F07
HR 4182 uint16 RW V ×0.01 F08
HR 4183 uint16 RW V ×0.01 F09
HR 4184 uint16 RW V ×0.01 F10
HR 4185 uint16 RW V ×0.01 F11
HR 4186 uint16 RW s F12
HR 4238 uint16 RW P00
HR 4239 uint16 RW P01
HR 4240 uint16 RW P02
HR 4241 uint16 RW P03
HR 4242 uint16 RW P05
HR 4243 uint16 RW P06
HR 4244 uint16 RW P07: 11 = LinkedGo 3.0
HR 4246 uint16 RW P08
HR 8449 uint16 R °C ×0.1 O00
HR 8450 uint16 R % ×0.1 O01
HR 8451 uint16 R °C ×0.1 O02; the manual does not name this value
HR 8464 bool bit 0 R 1 = relay closed
HR 8464 bool bit 1 R
HR 8464 bool bit 2 R
HR 8464 bool bit 3 R
HR 8464 bool bit 4 R
HR 8464 bool bit 5 R
HR 8474 bool bit 0 R Alarm E03

Help improve this map

Esc