WAGO 879-3000 energy meter Modbus register map

Also covers 879-3001, 879-3020, 879-3021, 879-3040

Three-phase MID energy meter (4PU, 4PS and 2PU CT variants) with Modbus RTU

Official
147 registers
Modbus TCP and RTU
Revision 2 · 2026-11-10
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 TCP and RTU
Unit ID: 1
TCP port: 502default
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: 147 holding registers
Groups: 4
Translation tables: 8
Revision: 2 · 2026-11-10
Added: 2026-10-18 (2026-10-18)
File: maps/wago/879-3000.mbmap.json · 26 KB · history
SHA-256: 358d29c64826391bb0fef10242362a797494f77d2aee4c7660d18b886f03a11e
Manufacturer: wago.com

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 16384	uint32 ABCD
Firmware	Software version	holding 16391	float32 ABCD

Sources and notes

WAGO Energy Meters (MID), Operating Instructions 4PU/4PS/2PU CT · version 1.8, 2024-02
Appendix 3, Modbus register map (A3.2) and write registers (A3.3); every register address, length, unit, type and the Float ABCD order checked against it
Varitras/ha-wago, wago_879_api/registers.py (MIT licence)
First source of the map; cites manual EN V1.6

Source: WAGO Energy Meters (MID) operating instructions 4PU/4PS/2PU CT, English, V1.8 (02/2024), appendix 3 (A3.1 to A3.3)

Checked against the manufacturer's manual (V1.8, appendix 3). Addresses in the manual are hexadecimal (0x4000 is 16384) and every register is read with function 03.
Every measured value is a 32-bit IEEE float in two holding registers, high word first (the manual's 'Float ABCD'). Whole numbers are 16-bit signed, apart from the serial number, checksum, status word and S0 pulse width (two registers, 'HEX' or 'Signed' in the manual).
Power is in kW, kvar and kVA and energy in kWh and kvarh, as the manual lists them.
The 'total' energy registers follow the combination code (0x400F): 1 import only, 2 export only, 3 import plus export, 4 and 5 import minus export. They can fall or go negative; use the import and export registers for rising counters.
Voltage average, current average and the CT ratio sit on registers the manual marks with an asterisk or grey: a direct-measuring meter leaves them at zero. A tariff-less meter holds zero in most T1 to T4 and Q1 to Q4 counters.
The meter has an RS-485 Modbus RTU interface, factory settings unit id 1, 9600 baud, 8 data bits, no parity, 1 stop bit. The manual does not describe Modbus TCP: the TCP access in the Home Assistant integration goes through the 879-9000 module, which forwards the meter's unit id and answers itself on unit 255.
The settings registers are writable with function 06 (function 16 for two-register values); access RW marks the ones the manual lists in A3.3. Not mapped: reserved registers, checksum 2, and the CT ratio history registers' meaning beyond their names.

Area	Address	Type	Access	Unit	Description
HR	16384	uint32 ABCD	R		Two registers, shown as hex
HR	16386	uint16	R		Variant code: 1111 on the 4PU, 1112 on the 4PS, 1113 on the 2PU CT
HR	16387	int16	RW		Unit id, 1 to 247 (0 is broadcast); written with function 06
HR	16388	int16	RW
HR	16389	float32 ABCD	R
HR	16391	float32 ABCD	R
HR	16393	float32 ABCD	R
HR	16395	int16	R	A	Rated current of the meter (the manual calls it meter amp)
HR	16396	uint16	R	A	One-register CT ratio; the two-register value at 0x401F is the one the manual shows how to write
HR	16397	float32 ABCD	RW	pulse/kWh	Pulses per kWh of the S0 output: 10000, 2000, 1000, 100, 10, 1, 0.1 or 0.01
HR	16399	int16	R		What the 'total' energy registers accumulate
HR	16400	uint16	RW	s	Display scroll time, 1 to 30 s
HR	16401	int16	RW
HR	16402	uint16	R		One ASCII character: F for import, R for export
HR	16403	uint16	R		One ASCII character: F for import, R for export
HR	16404	uint16	R		One ASCII character: F for import, R for export
HR	16406	int16	RW		Write 0 to reset
HR	16407	int16	R
HR	16408	int16	R
HR	16409	int16	R
HR	16410	int16	R
HR	16411	uint32 ABCD	R		Two registers, shown as hex
HR	16413	uint32 ABCD	R		Two registers, shown as hex
HR	16415	uint16	RW		First half of the two-register CT ratio at 0x401F: the primary current, written together with the secondary (9995/5 in the manual example). Zero on a direct-measuring meter
HR	16416	uint16	RW		Second half of the two-register CT ratio at 0x401F: the secondary current. Zero on a direct-measuring meter
HR	16417	uint16	RW	ms	S0 pulse width, 2 to 99 ms (the read table gives two registers, the write table one; mapped as one because the next register is 0x4022)
HR	16418	uint16	RW
HR	16422	int16	RW		Value format of the meter: standard or integer
HR	16434	int16	RW
HR	16435	int16	RW
HR	20480	float32 ABCD	R	V
HR	20482	float32 ABCD	R	V
HR	20484	float32 ABCD	R	V
HR	20486	float32 ABCD	R	V
HR	20488	float32 ABCD	R	Hz
HR	20490	float32 ABCD	R	A
HR	20492	float32 ABCD	R	A
HR	20494	float32 ABCD	R	A
HR	20496	float32 ABCD	R	A
HR	20498	float32 ABCD	R	kW
HR	20500	float32 ABCD	R	kW
HR	20502	float32 ABCD	R	kW
HR	20504	float32 ABCD	R	kW
HR	20506	float32 ABCD	R	kvar
HR	20508	float32 ABCD	R	kvar
HR	20510	float32 ABCD	R	kvar
HR	20512	float32 ABCD	R	kvar
HR	20514	float32 ABCD	R	kVA
HR	20516	float32 ABCD	R	kVA
HR	20518	float32 ABCD	R	kVA
HR	20520	float32 ABCD	R	kVA
HR	20522	float32 ABCD	R
HR	20524	float32 ABCD	R
HR	20526	float32 ABCD	R
HR	20528	float32 ABCD	R
HR	20530	float32 ABCD	R	V
HR	20532	float32 ABCD	R	V
HR	20534	float32 ABCD	R	V
HR	24576	float32 ABCD	R	kWh
HR	24578	float32 ABCD	R	kWh
HR	24580	float32 ABCD	R	kWh
HR	24582	float32 ABCD	R	kWh
HR	24584	float32 ABCD	R	kWh
HR	24586	float32 ABCD	R	kWh
HR	24588	float32 ABCD	R	kWh
HR	24590	float32 ABCD	R	kWh
HR	24592	float32 ABCD	R	kWh
HR	24594	float32 ABCD	R	kWh
HR	24596	float32 ABCD	R	kWh
HR	24598	float32 ABCD	R	kWh
HR	24600	float32 ABCD	R	kWh
HR	24602	float32 ABCD	R	kWh
HR	24604	float32 ABCD	R	kWh
HR	24606	float32 ABCD	R	kWh
HR	24608	float32 ABCD	R	kWh
HR	24610	float32 ABCD	R	kWh
HR	24612	float32 ABCD	R	kvarh
HR	24614	float32 ABCD	R	kvarh
HR	24616	float32 ABCD	R	kvarh
HR	24618	float32 ABCD	R	kvarh
HR	24620	float32 ABCD	R	kvarh
HR	24622	float32 ABCD	R	kvarh
HR	24624	float32 ABCD	R	kvarh
HR	24626	float32 ABCD	R	kvarh
HR	24628	float32 ABCD	R	kvarh
HR	24630	float32 ABCD	R	kvarh
HR	24632	float32 ABCD	R	kvarh
HR	24634	float32 ABCD	R	kvarh
HR	24636	float32 ABCD	R	kvarh
HR	24638	float32 ABCD	R	kvarh
HR	24640	float32 ABCD	R	kvarh
HR	24642	float32 ABCD	R	kvarh
HR	24644	float32 ABCD	R	kvarh
HR	24646	float32 ABCD	R	kvarh
HR	24648	int16	RW		Active tariff, 1 to 4; written with function 06
HR	24649	float32 ABCD	RW	kWh	Resettable day register; write zero to reset it
HR	24651	float32 ABCD	R	kWh
HR	24653	float32 ABCD	R	kWh
HR	24655	float32 ABCD	R	kWh
HR	24657	float32 ABCD	R	kWh

Help improve this map

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Suggest a correctionEdit the file on GitHub; it opens a pull request.
Report a problemA wrong address, type, scale or byte order.
Read the formatWhat each key of the file means (SPEC.md).