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VRF / split AC gateway · Modbus register map
Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway Modbus register map
Updated 24 October 2026
Modbus RTU server that plugs into the CN65/CN12/CN6 connector on a Fujitsu indoor unit's control board with the supplied cable. Holding registers give on/off, mode, fan (up to 6 speeds), both vanes, economy, antifreeze, setpoint and limits, room and return temperatures, filter sign, alarm and error code, plus window-contact and external-temperature functions.
This page lists 35 Modbus registers for the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway — 18 writable — with the table, 0-based wire address, data type, word order, scale, units and access of each, re-typed from Intesis (HMS Networks)’s own free documentation (linked below) and checked against it.
- Manufacturer
- Intesis (HMS Networks)
- Model
- INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway
- Equipment type
- VRF / split AC gateway
- Registers
- 35 (18 writable)
- Transport
- Modbus RTU
- Default unit ID
- 1
- Default serial
- 9600 baud, 8N2
- Documented addressing
- 0-based (the number printed is the address on the wire)
- Also known as
- INMBSFGL001I000, FJ-AC-MBS-1, Intesis Fujitsu domestic Modbus
Integration notes: Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway
Plug the supplied cable into CN65/CN12/CN6 on the indoor board, set the fan-speed count and baud on SW1 and the address on SW2, power-cycle, then poll holding registers 0-11 with function 03 and write with 06.
Minimum registers to map
Addresses are 0-based wire addresses. Enough to monitor and run the unit; map more as the job needs.
| Register | Name | Type | Why | Access |
|---|---|---|---|---|
| HR 0 | AC unit On/Off | UINT16 | On/off | Read/write |
| HR 1 | AC unit mode | UINT16 | Mode | Read/write |
| HR 2 | AC unit fan speed | UINT16 | Fan speed | Read/write |
| HR 4 | AC unit temperature setpoint | UINT16 | Setpoint | Read/write |
| HR 5 | AC unit temperature reference | UINT16 | Room temperature | Read |
| HR 10 | AC unit alarm status | UINT16 | Alarm flag | Read |
| HR 11 | Error code | UINT16 | Error code | Read |
Enable Modbus control & writes
No enable step; register 7 (gateway disablement) must be 0 for commands to reach the unit.
Byte order & addressing
- Temperature scale depends on DIP SW2 and the manual is inconsistent about the factory default.
- 8-N-2 by default; 8-N-1 is auto-detected.
- Function 16 is accepted only with a quantity of one register; functions 3 and 4 both read the same holding registers.
Network setup
- SW1 positions 1-2: number of fan speeds (3/4/5/6, default 4); positions 6-8: baud (9600 default).
- SW2 positions 1-6: slave address (default 1); position 7: x1/x10; position 8: °C/°F.
- SW3: 120 Ω termination (position 1) and bus biasing (positions 2-3, both on).
- DIP changes need a power cycle. The Modbus terminal is B, A, SG; EIA-485 max 1,200 m.
Watch out for
- The gateway only answers once it is connected to a powered indoor unit.
- Register 22 (external temperature) needs the indoor unit set to use the remote-controller thermostat (Fujitsu function 42 = 1, set by an installer) and has no effect on RAC models that need an extra comms accessory.
Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway Modbus registers
Address = 0-based wire address (the documented number is shown under it when it differs) · Order: ABCD = high word first, CDAB = low word first · Scale: engineering value = raw × scale.
| Table | Address | Name | Description | Type | Order | Scale | Units | Access | Values / bits |
|---|---|---|---|---|---|---|---|---|---|
| HR | 0 | AC unit On/Off | UINT16 | Read/write | 0 = Off; 1 = On | ||||
| HR | 1 | AC unit mode | Available modes depend on the indoor unit. | UINT16 | Read/write | 0 = Auto; 1 = Heat; 2 = Dry; 3 = Fan; 4 = Cool | |||
| HR | 2 | AC unit fan speed | Speed count (3-6) set on SW1; available speeds depend on the unit. | UINT16 | Read/write | 0 = Auto; 1 = Quiet; 2 = Low; 3 = Med; 4 = High | |||
| HR | 3 | AC unit vane position | Up/down vane; availability depends on the indoor unit. | UINT16 | Read/write | 1 = Position-1 (Horizontal); 2 = Position-2 (Horizontal); 3 = Position-3 (Medium); 4 = Position-4 (Vertical); 10 = Swing | |||
| HR | 4 | AC unit temperature setpoint | Setpoint 16..30 °C (61..86 °F). SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read/write | 0 = Undetermined; 32768 = Initialisation value / no value (0x8000; manual writes -32768) | ||
| HR | 5 | AC unit temperature reference | Room temperature, 18..30 °C. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | 0 = Undetermined; 32768 = No temperature sent from the remote controller (0x8000) | ||
| HR | 6 | Window contact | Virtual window contact written from Modbus. | UINT16 | Read/write | 0 = Closed; 1 = Open | |||
| HR | 7 | Gateway disablement | Stops the gateway passing commands; stored in NVM. | UINT16 | Read/write | 0 = INMBSFGL001I000 enabled; 1 = INMBSFGL001I000 disabled | |||
| HR | 8 | AC remote control disablement | Blocks the Fujitsu wired remote. | UINT16 | Read/write | 0 = Remote control enabled; 1 = Remote control disabled | |||
| HR | 9 | AC unit operation time | Hours the unit has been on. | UINT16 | h | Read/write | |||
| HR | 10 | AC unit alarm status | UINT16 | Read | 0 = No alarm condition; 1 = Alarm condition | ||||
| HR | 11 | Error code | Fujitsu error number (manual section 7); 65535 = communication error. | UINT16 | Read | 0 = No error present; 65535 = Communication error (gateway or remote controller with the AC unit) | |||
| HR | 13 | Open window switch-off timeout | Countdown after window opens before switch-off (0..30, default 30). | UINT16 | min | Read/write | |||
| HR | 14 | Modbus RTU baud rate | Baud rate in use (set on DIP switches). | UINT16 | Read | ||||
| HR | 15 | Modbus slave address | Range 1..63. | UINT16 | Read | ||||
| HR | 21 | Number of fan speeds | 3..6, as set on SW1. | UINT16 | Read | ||||
| HR | 22 | External ambient temperature (Modbus) | Modbus room sensor; RAC caveat in gotchas. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read/write | 32768 = Initialisation value, no external sensor value (0x8000) | ||
| HR | 23 | AC real temperature setpoint | Setpoint applied in the unit, 16..31 °C. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | |||
| HR | 24 | Current AC max setpoint | Upper setpoint limit reported by the unit. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | 32768 = Initialisation value / no value (0x8000; manual writes -32768) | ||
| HR | 25 | Current AC min setpoint | Lower setpoint limit reported by the unit. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | 32768 = Initialisation value / no value (0x8000; manual writes -32768) | ||
| HR | 26 | AC unit horizontal vane position | Left/right vane; manual prints 1 and 5 with an ellipsis for positions in between. | UINT16 | Read/write | 0 = Auto; 1 = Position 1; 5 = Position 5; 10 = Swing | |||
| HR | 31 | Window contact status (feedback) | UINT16 | Read | 0 = Not active; 1 = Active (window open) | ||||
| HR | 36 | External On/Off disablement | UINT16 | Read/write | 0 = Not active; 1 = Active | ||||
| HR | 40 | Window contact On/Off disablement | Whether the window-contact function is in use. | UINT16 | Read | 0 = Window contact disabled (not working); 1 = Window contact enabled (in use) | |||
| HR | 43 | Filter reset | Write 1 to reset the filter sign. | UINT16 | Write | 1 = Reset | |||
| HR | 44 | Filter status | UINT16 | Read | 0 = Off; 1 = Lit | ||||
| HR | 49 | Device ID | Reads 0x0D00. | UINT16 | Read | ||||
| HR | 50 | Software version | UINT16 | Read | |||||
| HR | 56 | Antifreeze operation | UINT16 | Read/write | 0 = Disabled; 1 = Enabled | ||||
| HR | 64 | Economy | UINT16 | Read/write | 0 = Disabled; 1 = Enabled | ||||
| HR | 65 | Input reference temperature | Reference temperature in use. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | 32768 = No external sensor value, no virtual temperature (0x8000) | ||
| HR | 66 | Return path temperature | Indoor unit return-air sensor. SW2 x1 °C assumed (x10: 0.1, or °F). | UINT16 | °C | Read | 32768 = Initialisation value / no value (0x8000; manual writes -32768) | ||
| HR | 97 | Block periodic sendings | 1 = only forward Modbus writes that change the value. | UINT16 | Read/write | 0 = Non-blocked; 1 = Blocked | |||
| HR | 98 | Master/Slave (gateway role) | UINT16 | Read | 0 = Slave; 1 = Master | ||||
| HR | 99 | Reset | Write 1 to restart the gateway. | UINT16 | Write | 1 = Reset |
Notes on this map
- The manual declares every register a 16-bit unsigned holding register; the temperature ranges listed never go below zero, so temperatures are UINT16. The 'no value' marker the manual writes as -32768 is raw 0x8000 (32768) and is listed as an enum entry. A value of 0 in the setpoint / reference registers means 'undetermined'.
- Temperature registers depend on the DIP SW2 positions 7-8 setting: x1 °C, x10 °C (decidegrees) or °F (no °F x10). The register-table footnote calls x10 the default, but the SW2 DIP-switch table marks x1 and °C as the defaults, so scale 1 / °C is used. Check the switch on site: if x10 is set use scale 0.1; if °F is set the values are whole °F.
- On this model the DIP switches are SW1 (fan speeds + baud), SW2 (address + temperature format) and SW3 (termination + bus biasing). Some lines in the manual (mechanical table, termination text) still say SW3/SW4 from other gateways; the DIP-switch tables are followed here.
- Fujitsu states the room temperature value is for display only and may not always match the actual room temperature.
- Error code enum (Fujitsu codes) not reproduced; see manual section 7.
- Horizontal vane (register 26): the manual lists only 1 = Position 1 and 5 = Position 5 with an ellipsis between, so values 2-4 are not listed here.
Check it against the live device. A register map tells you what the controller can expose; the unit in front of you may differ by firmware or options. Read a few registers and compare them with the unit’s own display; for a 32-bit value the float and byte-order decoder shows all four word orders at once, so a wrong word order or scale is obvious. New to this? Read what a register map is and why addresses are off by one.
Questions about the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway
What Modbus registers does the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway have?
This map lists 35 registers: 35 holding registers. 18 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.
Are the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway Modbus addresses 0-based or 1-based?
The manufacturer's document numbers registers 0-based (the number printed is the address on the wire). Every address on this page is the 0-based wire address you put in the request; the documented number is shown under it where it differs. Tables give a 'protocol address' (base 0) and a 'PLC address' (base 1); the protocol address is the wire address and is used for 'documented'.
What are the minimum Modbus registers to integrate the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway?
Start with HR 0 AC unit On/Off (On/off); HR 1 AC unit mode (Mode); HR 2 AC unit fan speed (Fan speed); HR 4 AC unit temperature setpoint (Setpoint); HR 5 AC unit temperature reference (Room temperature); HR 10 AC unit alarm status (Alarm flag); HR 11 Error code (Error code).
How do I enable Modbus control of the Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway?
No enable step; register 7 (gateway disablement) must be 0 for commands to reach the unit.
Where is the official Intesis (HMS Networks) INMBSFGL001I000 Fujitsu domestic AC to Modbus RTU gateway Modbus documentation?
The source is Intesis INMBSFGL001I000 Modbus RTU Gateway - Fujitsu Air Conditioning - User Manual (User Manual v1.5 EN), revision 2024-01, published free by Intesis (HMS Networks) at https://www.hms-networks.com/docs/default-source/products/intesis/manuals-and-guides---manuals/user-manual-inmbsfgl001i000.pdf.
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Also known as: INMBSLGE001R000, LG-RC-MBS-1, Intesis LG Modbus - VRF / split AC gateway
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Mitsubishi Heavy Industries indoor units (one, or up to 16 controlled together as one) on the XY remote-controller bus, user manual r6.4 (01/2024).
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Source: Intesis INMBSFGL001I000 Modbus RTU Gateway - Fujitsu Air Conditioning - User Manual · User Manual v1.5 EN · rev. 2024-01. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.