Mitsubishi ATW heat pump (needs MelcoBEMS MINI A1M)

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire; word order and scaling are only confirmed at the hardware-verified rung.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale	unit
system_on_off	25	U16	1
operating_mode	26	U16	1
set_tank_water_temperature_signed	30	I16	0.01	°C
set_tank_water_temperature	31	U16	0.01	°C
hc_thermostat_target_temperature_zone_1_signed	32	I16	0.01	°C
hc_thermostat_target_temperature_zone_1	33	U16	0.01	°C
hc_thermostat_target_temperature_zone_2_signed	34	I16	0.01	°C
hc_thermostat_target_temperature_zone_2	35	U16	0.01	°C
outdoor_temperature_by_bms_signed	50	I16	0.1	°C
outdoor_temperature_by_bms	51	U16	0.1	°C
setting_water_temperature_signed	52	I16	0.01	°C
setting_water_temperature	53	U16	0.01	°C
thermostat_target_temperature_zone_1_signed	54	I16	0.01	°C
thermostat_target_temperature_zone_1	55	U16	0.01	°C
thermostat_target_temperature_zone_2_signed	56	I16	0.01	°C
thermostat_target_temperature_zone_2	57	U16	0.01	°C
heat_pump_frequency_master	73	U16	1	Hz
temperature_setpoint_zone_1_signed	81	I16	0.01	°C
temperature_setpoint_zone_1	82	U16	0.01	°C
temperature_setpoint_zone_2_signed	83	I16	0.01	°C
temperature_setpoint_zone_2	84	U16	0.01	°C
flow_temperature_setpoint_zone_1_signed	85	I16	0.01	°C
flow_temperature_setpoint_zone_1	86	U16	0.01	°C
flow_temperature_setpoint_zone_2_signed	87	I16	0.01	°C
flow_temperature_setpoint_zone_2	88	U16	0.01	°C
room_temperature_zone_1_signed	93	I16	0.01	°C
room_temperature_zone_1	94	U16	0.01	°C
room_temperature_zone_2_signed	95	I16	0.01	°C
room_temperature_zone_2	96	U16	0.01	°C
refrigerant_liquid_temperature_signed	97	I16	0.01	°C
refrigerant_liquid_temperature	98	U16	0.01	°C
outdoor_ambient_temperature_signed	99	I16	0.1	°C
outdoor_ambient_temperature	100	U16	0.1	°C
flow_temperature_signed	101	I16	0.01	°C
flow_temperature	102	U16	0.01	°C
return_temperature_signed	103	I16	0.01	°C
return_temperature	104	U16	0.01	°C
tank_water_temperature_signed	105	I16	0.01	°C
tank_water_temperature	106	U16	0.01	°C
boiler_flow_temperature_signed	115	I16	0.01
boiler_flow_temperature	116	U16	0.01
boiler_return_temperature_signed	117	I16	0.01
boiler_return_temperature	118	U16	0.01
evaporating_temperature_signed	230	I16	0.01
evaporating_temperature	231	U16	0.01
condensing_temperature_signed	232	I16	0.01
condensing_temperature	233	U16	0.01
flow_rate	299	U16	1

link settings as documented (unverified): baud 1200/2400/4800/9600/14400/19200/28800/38400/56000/57600/115200; FC 01,02,03,04,05,06,15,16

bench facts as documented (unverified)

terminals	RS-485
firmware register	Holding 10, Input 3
doc revision	1.0.4
firmware applicability	3.0.25

generated by gemini:gemini-3.5-flash · harvested from https://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006/MelcoBEMS_MINI_(A1M)-ATW_Modbus_Register_Tables_V1.0.4_fw3.0.25.pdf (Mitsubishi Electric); manual-faithful — the document's claims, panel risk: ELEVATED — panel is not confident; proved interop-verified on 2026-06-10 · recorded 2026-06-10

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

Have a device that isn't here? Upload its register map — generation is free, and the connector earns its rung by being proven, not claimed.

Need it proven on your own device? Hardware verification — if it doesn't verify, you don't pay.

Building a platform? License the verified library — machine-readable maps, firmware matrix, API access.