Novus RHT Climate Modbus register map

Also covers RHT Climate WM, RHT Climate DM

Temperature and humidity transmitter (wall and duct mount) with two analog outputs, two alarm outputs, buzzer and Modbus RTU over RS485: temperature, humidity and psychrometric values, min/max, outputs, alarms, forcing and diagnostics

Official
126 registers
Modbus RTU
Revision 1 · 2026-10-31
Identity: firmware, serial number

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.

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Communication

Protocol: Modbus RTU
Unit ID: 1
Serial: 19200 8N1 · 19200 baud, 8 data bits, none parity, 1 stop bit
Byte / word order: CDAB · bytes big-endian, words low first (word swap)
Addresses: 0-based

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

Map

Registers: 126 holding registers
Groups: 13
Translation tables: 4
Revision: 1 · 2026-10-31
Firmware: from 1.4 V1.4x or later
Added: 2026-10-31 (2026-10-31)
File: maps/novus/rht-climate.mbmap.json · 27 KB · history
SHA-256: e31d5d871dd05e9086ce37c645de327b4640c6a7482247767a9b51c6ab818b46
Manufacturer: novus.com.br

Device identity

What a tool can read to check that this map fits the connected device (SPEC.md section 4.7). Registers with a role are read like any other register.

Registers
Role	Register	Address	Type	Values
Serial number	Serial number	holding 300	uint32 ABCD
Firmware	Firmware version	holding 302	uint16

Sources and notes

Transmissor RHT Climate, modelos WM e DM - Manual de Instruções · version V1.4x I
linked in issue #93; section 10.1 and the option tables of chapter 7

Source: Novus RHT Climate WM / DM instruction manual V1.4x I (Portuguese), chapters 7 and 10

Functions 03, 05, 06 and 16; writes with address 0 are broadcast.
Serial defaults: address 1, 19200 bit/s, no parity. The device answers whatever the stop bits are.
32-bit values are two registers, least significant word first; every register is big-endian. Both registers of a 32-bit value must be read or written together.
The measurements are shown with two decimals. Units follow the unit system (register 127): SI (°C, mbar, g/m³, g/kg, kJ/kg) or US (°F, psi, gr/ft³, gr/lb, BTU/lb).
The manual does not give the decimals of the 32-bit output limits and alarm setpoints; this map reads them with two decimals, like the measurements. Their ranges depend on the quantity chosen for the output or alarm.
Settings with an input pair (103-106, 115-118, 135-138, 152-155, 169-172) are copied to the working pair (108-111, 120-123, 145-148, 162-165, 179-182) when in range; out-of-range inputs are flagged in register 343.
Alarm 3 in the register table is the buzzer (models with display).
Written from the manufacturer's manual; not tested on a device.

Area	Address	Type	Access	Unit	Scale	Description
HR	0	int32 CDAB	R	%RH	×0.01	%RH
HR	2	int32 CDAB	R		×0.01	°C (°F in US units)
HR	4	int32 CDAB	R		×0.01	°C (°F in US units)
HR	6	int32 CDAB	R		×0.01	°C (°F in US units)
HR	8	int32 CDAB	R		×0.01	°C (°F in US units)
HR	10	int32 CDAB	R		×0.01	kJ/kg (BTU/lb in US units)
HR	12	int32 CDAB	R		×0.01	g/m³ (gr/ft³ in US units)
HR	14	int32 CDAB	R		×0.01	mbar (psi in US units)
HR	16	int32 CDAB	R		×0.01	g/kg (gr/lb in US units)
HR	18	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	20	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	22	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	24	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	26	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	28	int32 CDAB	R		×0.01	The manual gives a range of 0-1000 for this pair, unlike the measurement; read here with two decimals like the measurement
HR	217	uint16	RW			Write 1 to reset every minimum and maximum
HR	101	uint16	RW
HR	102	uint16	RW
HR	103	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 108 when valid
HR	105	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 110 when valid
HR	107	uint16	RW
HR	108	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	110	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	113	uint16	RW
HR	114	uint16	RW
HR	115	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 120 when valid
HR	117	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 122 when valid
HR	119	uint16	RW
HR	120	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	122	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	133	uint16	RW
HR	134	uint16	RW
HR	135	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 145 when valid
HR	137	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 147 when valid
HR	139	uint16	RW
HR	140	uint16	RW		×0.1	In the unit of the alarm quantity
HR	141	uint16	RW	s
HR	142	uint16	RW	s
HR	143	uint16	RW
HR	144	uint16	RW
HR	145	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	147	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	150	uint16	RW
HR	151	uint16	RW
HR	152	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 162 when valid
HR	154	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 164 when valid
HR	156	uint16	RW
HR	157	uint16	RW		×0.1	In the unit of the alarm quantity
HR	158	uint16	RW	s
HR	159	uint16	RW	s
HR	160	uint16	RW
HR	161	uint16	RW
HR	162	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	164	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	167	uint16	RW
HR	168	uint16	RW
HR	169	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 179 when valid
HR	171	int32 CDAB	RW		×0.01	Two decimals assumed, as in the measurements; copied to register 181 when valid
HR	173	uint16	RW
HR	174	uint16	RW		×0.1	In the unit of the alarm quantity
HR	175	uint16	RW	s
HR	176	uint16	RW	s
HR	177	uint16	RW
HR	178	uint16	RW
HR	179	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	181	int32 CDAB	R		×0.01	Two decimals assumed, as in the measurements
HR	125	uint16	RW	s
HR	126	uint16	RW	s
HR	127	uint16	RW
HR	192	int16	RW		×0.1	±5.0 °C (±9.0 °F)
HR	193	int16	RW	%RH	×0.1
HR	200	uint16	RW			Used for the psychrometric calculations: 1013 = 1013 mbar in SI units, 147 = 14.7 psi in US units
HR	187	uint16	RW
HR	209	uint16	RW
HR	221	uint16	RW
HR	222	uint16	RW
HR	201	uint16	RW
HR	202	uint16	RW			0-10.00 V or 3.6-21.00 mA; the manual does not give the encoding
HR	203	uint16	RW
HR	204	uint16	RW			0-10.00 V or 3.6-21.00 mA; the manual does not give the encoding
HR	205	uint16	RW
HR	206	uint16	RW
HR	207	uint16	RW
HR	208	uint16	RW
HR	211	uint16	RW
HR	212	uint16	RW
HR	213	uint16	RW
HR	215	uint16	RW
HR	214	uint16	RW	%RH	×0.1
HR	216	int16	RW		×0.1	°C (°F in US units)
HR	184	uint16	RW
HR	185	uint16	RW
HR	186	uint16	RW
HR	341	bool bit 1	R
HR	341	bool bit 2	R
HR	341	bool bit 3	R
HR	341	bool bit 4	R
HR	341	bool bit 5	R
HR	341	bool bit 6	R
HR	341	bool bit 7	R

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Report a problemA wrong address, type, scale or byte order.
Read the formatWhat each key of the file means (SPEC.md).