What are the M4M's RS-485 settings?

Address 1 to 247; 9600, 19200, 38400, 57600 or 115200 bit/s; even, odd or no parity; 1 or 2 stop bits. Set them under Communication > Modbus RTU on the display.

Which function codes does the M4M support?

Function code 3 to read holding registers, and 6 and 16 to write. After a write, read the value back: the meter does not report whether a write took effect, and silently ignores writes to settings the model does not have.

How are 32-bit values ordered?

The most significant byte is in the high byte of the first register and the least significant byte in the low byte of the last. In Edge that is big-endian with no word or byte swap.

What is the difference between the M4M 20 and the M4M 30?

The M4M 30 has a fourth current input for neutral, a touchscreen instead of buttons and more programmable I/O. Both have Class 0.5S active energy and the same common register map.

ABB M4M 20 and M4M 30 Modbus register map

Compatibility

Compatible with EpiSensor Edge over Modbus RTU and Modbus TCP.

Connect its RS-485 port to a Modbus Interface or to a serial interface on the Gateway, or use its Ethernet port for Modbus TCP. Edge polls it with its Modbus client.

Edge reads 32 values from it, listed under Interface.

Connect it with

Modbus Interface ZMB-3X
From €399 ex VAT Configure Modbus Interface
Gateway ZGW-20
From €899 ex VAT Configure Gateway

Specifications

The M4M 20 and M4M 30 are ABB's panel-mounted network analysers for low-voltage switchboards. Both fit a 96 × 96 mm cutout, take a 48 to 240 V AC/DC auxiliary supply and measure up to 400 V phase to neutral and 690 V between phases directly. Current comes from x/1 A or x/5 A transformers, or from ABB's R4M Rogowski coils on the Rogowski versions. The M4M 20 has three current inputs and five buttons; the M4M 30 adds a fourth input for neutral and a touchscreen.^1, 2

Power: Mains. Auxiliary supply of 48 to 240 V AC or DC (±15 %), 50 or 60 Hz, 10 VA at most, protected by a T1 A fuse.¹
Active energy accuracy: Class 0.5S (IEC 62053-22) with 5 A or 1 A CTs¹
Reactive energy accuracy: Class 2S (IEC 62053-23)¹
Performance class: IEC 61557-12 PMD/S/K70/0,5; voltage and current Class 0.2¹
Voltage inputs: 46 to 400 V AC L-N, 80 to 690 V AC L-L (+20 %), CAT III¹
Current inputs: 3 on the M4M 20, 4 with neutral on the M4M 30; x/5 A or x/1 A, 50 mA to 6 A²
Measurement: True RMS to the 40th harmonic, 128 samples a cycle, refreshed every 25 cycles¹
Communication versions: Modbus RTU, Modbus TCP, Profibus DP-V0 or BACnet/IP, each with Bluetooth Low Energy¹
Dimensions: 96 × 96 × 77.5 mm, 57 mm deep inside the board¹
Protection: IP54 front, IP20 terminals¹
Operating temperature: -25 to 70 °C, up to 93 % RH non-condensing at 40 °C¹

Where it is used

Incomers, feeders and motor control centres in low-voltage switchboards, on existing CTs or Rogowski coils.
Transformer and distribution board monitoring
Power quality on circuits with drives, UPS systems and IT loads, with THD per phase.
Data centre power monitoring and PUE inputs
Bringing meters already on a Modbus RTU bus or the site network into a BMS or SCADA system through Edge.
Modbus meter integration for a BMS or SCADA system

Interface

This register map applies to the M4M 20 and M4M 30.

Communication settings

Modbus RTU: RS-485 with optical isolation, on the Modbus, I/O and Rogowski versions
Connector: 3-pole terminal: A, B and common
Unit address: 1 to 247
Baud rate: 9600, 19200, 38400, 57600 or 115200 bit/s
Parity: Even, odd or none
Stop bits: 1 or 2
Modbus TCP: RJ45 on the Ethernet versions, up to 3 clients
TCP defaults: DHCP off, 192.168.1.12, gateway 192.168.1.1, port 502
Bluetooth: Bluetooth Low Energy on every version, for set-up with ABB's apps
Read with: FC03 (holding registers)
Word order: High word first on each 32-bit value
Addresses: Zero-based PDU addresses, as sent on the bus

From M4M 20 network analyzer user manual (2CSG445032D0201)¹ and M4M Modbus communication manual (2CSG445050D0201)³.

Register map

Download

Point	Address	Hex	Format	Scale	Unit
Voltage L1-N	23298	`0x5B02`	UINT32	×0.1	V
Voltage L2-N	23300	`0x5B04`	UINT32	×0.1	V
Voltage L3-N	23302	`0x5B06`	UINT32	×0.1	V
Voltage L1-L2	23304	`0x5B08`	UINT32	×0.1	V
Voltage L3-L2	23306	`0x5B0A`	UINT32	×0.1	V
Voltage L1-L3	23308	`0x5B0C`	UINT32	×0.1	V
Current L1	23312	`0x5B10`	UINT32	×0.01	A
Current L2	23314	`0x5B12`	UINT32	×0.01	A
Current L3	23316	`0x5B14`	UINT32	×0.01	A
Total Active Power	23322	`0x5B1A`	INT32	×0.01	W
Active Power L1	23324	`0x5B1C`	INT32	×0.01	W
Active Power L2	23326	`0x5B1E`	INT32	×0.01	W
Active Power L3	23328	`0x5B20`	INT32	×0.01	W
Total Reactive Power	23330	`0x5B22`	INT32	×0.01	var
Reactive Power L1	23332	`0x5B24`	INT32	×0.01	var
Reactive Power L2	23334	`0x5B26`	INT32	×0.01	var
Reactive Power L3	23336	`0x5B28`	INT32	×0.01	var
Total Apparent Power	23338	`0x5B2A`	INT32	×0.01	VA
Apparent Power L1	23340	`0x5B2C`	INT32	×0.01	VA
Apparent Power L2	23342	`0x5B2E`	INT32	×0.01	VA
Apparent Power L3	23344	`0x5B30`	INT32	×0.01	VA
Frequency	23346	`0x5B32`	UINT16	×0.01	Hz
Total Power Factor	23360	`0x5B40`	INT16	×0.001	-
Power Factor L1	23361	`0x5B41`	INT16	×0.001	-
Power Factor L2	23362	`0x5B42`	INT16	×0.001	-
Power Factor L3	23363	`0x5B43`	INT16	×0.001	-
Voltage THD L1	23808	`0x5D00`	UINT16	×0.1	%
Voltage THD L2	23936	`0x5D80`	UINT16	×0.1	%
Voltage THD L3	24064	`0x5E00`	UINT16	×0.1	%
Current THD L1	24576	`0x6000`	UINT16	×0.1	%
Current THD L2	24704	`0x6080`	UINT16	×0.1	%
Current THD L3	24832	`0x6100`	UINT16	×0.1	%

Download the M4M 20 / M4M 30 register map as CSV

ABB gives each value's first register in hexadecimal, exactly as it goes on the bus. The addresses on this page are the same numbers in decimal: Voltage L1-N at 0x5B02 is 23298.³

The meter reads any 1 to 125 registers between 0x1000 and 0x8EFF in one request. A value the connected model does not have reads as all ones if unsigned, or the highest positive number if signed.³

Energy totals are 64-bit unsigned counters in steps of 0.01 kWh, starting at 0x5000 for imported active energy. They are not in the Edge template, because Edge does not read 64-bit integers.⁴

Edge template

This JSON file supplies the register map. Applying it to an existing meter replaces its sensor list while retaining the site connection, unit ID and enable state.

Model	Connection	Points	Version	Updated	Download
M4M 20 / M4M 30	Modbus RTU over RS-485, Modbus TCP	32	1.0.0	20 Sep 2026	Download

Downloads need a signed-in account with Edge download access.

Use the template in Edge

Import the JSON file
On the target Gateway in Edge, open Settings, then Device Templates. Choose Import and select the downloaded JSON file. Confirm that the model and template name match your device.
Load the map for your meter
In the Modbus device wizard, choose the site connection and unit ID, then use Load Template to select the imported map. For an existing device, apply the template to that exact model. Its connection, unit ID and enable state are retained.
Test a reading
Use Test in the wizard and compare a known reading with the meter display. Check its unit, sign and scale, then confirm that timestamps keep advancing. These starter maps are read-only and leave exports off until you configure them.

Setup

Check the version
Only the Modbus, I/O and Rogowski versions have Modbus RTU on RS-485. Ethernet versions speak Modbus TCP; Profibus and BACnet versions do not speak Modbus.¹
Commission the meter
On first power-up a wizard asks for language, password, date and time, network type, CT ratio and VT ratio. Set the CT ratio to your transformers before you read anything.²
Wire the bus
Connect A and B on the 3-pole terminal to a ZMB-31 or the Gateway's serial interface, with C to the common if you have one. Keep the bus under 700 m and stubs under 1 m, and terminate both ends with 120 Ω.³
Set address and speed
Under Communication > Modbus RTU, set an address from 1 to 247, the baud rate and the parity, then set Edge to match. On Ethernet versions, set the IP address or turn on DHCP under Communication > Modbus TCP/IP.¹
Read one register
Import the template and read Voltage L1-N at 23298 (0x5B02) with function code 3. It is an unsigned 32-bit value in steps of 0.1 V, so 2301 means 230.1 V.⁴
Enable the map
Once voltage, current and total active power match the display, enable the rest of the map and watch several fresh readings before you add exports or alarms.

Common questions

What are the M4M's RS-485 settings?: Address 1 to 247; 9600, 19200, 38400, 57600 or 115200 bit/s; even, odd or no parity; 1 or 2 stop bits. Set them under Communication > Modbus RTU on the display.¹
Which function codes does the M4M support?: Function code 3 to read holding registers, and 6 and 16 to write. After a write, read the value back: the meter does not report whether a write took effect, and silently ignores writes to settings the model does not have.³
How are 32-bit values ordered?: The most significant byte is in the high byte of the first register and the least significant byte in the low byte of the last. In Edge that is big-endian with no word or byte swap.³
What is the difference between the M4M 20 and the M4M 30?: The M4M 30 has a fourth current input for neutral, a touchscreen instead of buttons and more programmable I/O. Both have Class 0.5S active energy and the same common register map.^1, 2