ABB M4M 30 Modbus

Compatibility

Compatible through Modbus RTU

Edge reads the documented local Modbus interface through the connection path below. This is protocol compatibility, not a claim of a built-in device mapping.

M4M 30 MODBUS, order code 2CSG274761R4051 (M4M30RS485), using conventional CT inputs. Ethernet, Rogowski, I/O, BACnet, Profibus, MID and M4M32 variants are not interchangeable hardware.

Connect it with

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

Models

Specifications

The M4M map is deliberately explicit about engineering units and resolution. A voltage register contains an unsigned integer that must be scaled, whereas other values have different widths and signs. The standard Modbus variant also differs physically from the Ethernet and Rogowski models, even though one user manual covers them together.¹

Order code

2CSG274761R4051 / M4M30RS485⁴

Current inputs

Conventional 1 A or 5 A CT secondary; Rogowski is a separate version¹

Communications

Modbus RTU and Bluetooth; Bluetooth is not the polling path in this guide⁴

Serial parameters

Address 1–247; 9.6, 19.2, 38.4, 57.6 or 115.2 kbit/s; use the configured parity¹

Accuracy

M4M30 active energy class 0.5S to IEC 62053-22 under the stated measurement conditions¹

Installation envelope

Front IP54, terminals IP20; operating temperature −25 to +70 °C under manual conditions¹

Interface

Documented measurements and integration boundaries for M4M 30 Modbus.

• Phase voltage L1 at 0x5B02: two-register unsigned integer, resolution 0.1 V.
• Phase and line voltages, currents and frequency with their individual workbook resolutions.
• Signed and unsigned power quantities: use the declared data type rather than treating all measurements as FLOAT32.
• Active energy import at 0x5000: four registers, unsigned quantity, 0.01 kWh resolution.
• Demand, alarms and historical records have separate access procedures; historical selection can require writes.
• Meter identity, firmware and configuration to preserve the exact product and scaling context.
• Unavailable unsigned values are FFFF in every register; signed values use their maximum positive code. Keep these as unavailable, not as large real measurements.

Setup

1. Match the order code and CT input

   Confirm 2CSG274761R4051 and record firmware. This is the conventional-CT Modbus version, not the Rogowski or Ethernet model. Have the authorised installer verify wiring, phase assignment and CT primary/secondary settings.

2. Record the actual serial settings

   On the meter, open Configuration, Communication, Modbus RTU. Record address, baud rate and parity and enter those exact values in the Edge connection. Follow ABB’s bus topology and termination instructions and retain one master per segment.

3. Use literal addresses and complete values

   ABB’s Start Reg Hex is the address sent on the bus. Convert hex to decimal if the client requires it; do not subtract one. Read both registers of L1 voltage at 0x5B02 in one FC03 request.

4. Decode before expanding the point list

   Apply unsigned 32-bit decoding, most significant byte first, and the 0.1 V resolution for the voltage example. Compare the result with the meter display, then configure each further quantity from its own type, register count and resolution.

5. Separate live reads from historical selection

   Read-only live metering does not require output or setup commands. ABB’s historical interface uses a header selection procedure with writes; treat that as a separate reviewed workflow. Preserve unavailable markers and compare an import-energy delta with the display over a known interval.

Common questions

Should 0x5B02 become 23297?

No. ABB states that the hexadecimal start register is expressed exactly as sent on the bus. 0x5B02 is decimal 23298; no one-based correction is applied.²

Why does a float decoder give nonsense?

L1 phase voltage is an unsigned integer across two registers, with 0.1 V resolution. Reinterpretation as IEEE-754 FLOAT32 changes the meaning of those bits. Use the workbook’s data type and multiplier.³

Can I read historical records without any writes?

The historical interface selects records through header registers and writes before reading data blocks. That is separate from straightforward FC03 live measurements; do not include those selection commands in a read-only polling template.²

Does Bluetooth replace the RS-485 connection?

The exact product offers Bluetooth and Modbus RTU, but this Edge integration uses the documented RS-485 Modbus interface. Bluetooth commissioning is not a claim of an Edge Bluetooth driver.^1, 4