Eastron SDM630 Modbus register map and complete integration guide

The Eastron SDM630 is the most widely deployed 3-phase energy meter in the European prosumer and installer market. With ~100 Modbus registers, MID certification, and a direct 100A connection, it offers more functionality than virtually any competitor under €130. Despite its popularity, no single web resource combines the complete register map with wiring guidance, working code examples, and regulatory context - the official Eastron PDF is login-gated and poorly indexed, while top-ranking community pages show deliberately incomplete register tables.

This guide gives you the complete register reference, correct RS485 wiring, working Home Assistant and ESPHome integrations, and the regulatory framework around MID certification.

The ModbusCloud Gateway reads out an Eastron SDM630 through a ready-made Eastron SDM630 template, with no register programming required.

Variants: V1, V2, V3 and MCT

The SDM630 exists in three main generations plus the MCT (CT-operated) series:

Practical advice: For new installations, always buy V2 or later. The Net kWh register (import minus export) is essential for solar PV monitoring. V3 adds higher accuracy class but is functionally equivalent for monitoring purposes.

Modbus communication settings

All measurement data uses IEEE 754 Float32 encoding (2 registers per value), default byte order Big Endian, Most Significant Register First (ABCD). Maximum 80 registers (40 parameters) per request.

Key Modbus registers

Voltage (FC04, Input Registers)

Current

Power (active, apparent, reactive)

Energy (key registers for monitoring)

Configuration registers (FC03/FC16, Holding Registers)

RS485 wiring

The SDM630 has terminals labelled A (+), B (−) and GND on the communication side, plus load terminals for the actual power measurement.

A

signal (+)

B

signal (-)

GND

shield / ground

1. 1

   Cable selection

   Use Belden 9841 or equivalent shielded twisted-pair with 120Ω characteristic impedance. Do NOT use Cat5/Cat6 - the impedance is wrong and you'll get CRC errors. Comm terminals accept 0.5-1.5 mm² with 6-7 mm strip, M2.5 screws at 0.4 Nm.

2. 2

   Load connection

   Connect L1/L2/L3 and N to the input side of the meter (facing the main breaker). The output side feeds your distribution board. For PV monitoring: install the SDM630 immediately after the main breaker, before the split to house load and inverter. Load terminal torque: 3-3.5 Nm.

3. 3

   RS485 wiring

   A terminal to A terminal of your gateway, B to B. Connect cable shield to GND on one side only (usually at the gateway). Maximum 2 wires per terminal - this enforces daisy-chain topology, not a star.

4. 4

   Install termination resistors

   120Ω resistor (¼W minimum) at both ends of the bus. The SDM630 does NOT have built-in termination - add one manually between A and B at the last device on the line. Many gateways have a DIP switch for this.

5. 5

   Test communication

   Defaults: 9600 baud, 8N1, address 1. For Growatt inverters: set address to 2 (Growatt expects this). Test with a USB-RS485 adapter (FTDI chipset, NOT CH340) and free software like QModMaster before integrating.

Home Assistant integration

The following YAML works with an RS485-to-Ethernet gateway:

modbus:
  - name: sdm630
    type: rtuovertcp
    host: 192.168.1.50
    port: 502
    sensors:
      - name: "L1 voltage"
        address: 0
        input_type: input
        data_type: float32
        unit_of_measurement: V
        precision: 1
      - name: "Total power"
        address: 52
        input_type: input
        data_type: float32
        unit_of_measurement: W
      - name: "Total import"
        address: 72
        input_type: input
        data_type: float32
        unit_of_measurement: kWh
        device_class: energy
        state_class: total_increasing
      - name: "Total export"
        address: 74
        input_type: input
        data_type: float32
        unit_of_measurement: kWh
        device_class: energy
        state_class: total_increasing

For GUI-based setup without YAML: install the custom HACS integration partach/ha_sdm630 - it offers preset profiles (basic / basic-plus / full) for quick setup.

ESPHome integration

Use an ESP32 with a MAX3485 RS485 transceiver (3.3V logic, preferred over MAX485):

uart:
  rx_pin: GPIO16
  tx_pin: GPIO17
  baud_rate: 9600

sensor:
  - platform: sdm_meter
    phase_a:
      voltage:
        name: "SDM630 L1 voltage"
      current:
        name: "SDM630 L1 current"
      active_power:
        name: "SDM630 L1 power"
    frequency:
      name: "SDM630 frequency"
    import_active_energy:
      name: "SDM630 total import"
    export_active_energy:
      name: "SDM630 total export"
    update_interval: 10s
    address: 1

Set logger: baud_rate: 0 when using hardware UART, otherwise serial logging will interfere with RS485 communication.

Python (Raspberry Pi)

import sdm_modbus

device = sdm_modbus.SDM630(device="/dev/ttyUSB0", baud=9600)
data = device.read_all(sdm_modbus.registerType.INPUT)

print(f"L1: {data['voltage_l1']:.1f} V")
print(f"Import: {data['total_import_active_energy']:.2f} kWh")
print(f"Export: {data['total_export_active_energy']:.2f} kWh")

The sdm_modbus library (PyPI) is purpose-built for Eastron meters. For manual access, minimalmodbus works too: instrument.read_float(0, functioncode=4) reads register 0.

Solar inverter compatibility

MID certification and regulations

MID is legally required when billing energy to third parties (tenants, employees, charging customers) in most EU countries. The SDM630 holds MID certificate 0120/SGS0151 covering Module B+D.

Netherlands

Under the Metrologiewet, MID meters are mandatory for tenant billing. Since January 2026, MID is also required for ERE certificates at EV charging stations. For own-use monitoring (solar PV, energy optimization), MID is NOT required - use the cheaper non-MID variant.

Germany

MessEG §37 requires calibrated/MID meters for any commercial transaction including tenant billing, EEG feed-in metering, and EV charging. Electronic meters have an 8-year Eichfrist (calibration validity). Violations carry fines up to €50,000. For public EV charging, MID alone is insufficient - full Eichrechtskonformität is required (stricter than other EU countries).

International standards

The MID accuracy certification covers only active energy (kWh) - not reactive energy, apparent energy, THD, or other parameters. Class B (equivalent to IEC Class 1) means ±1% maximum error at reference conditions across 5%-120% of rated current.

Top 10 mistakes with SDM630 RS485

1. A/B swapped - Swap them. Won't damage anything.
2. GND not carried through between devices on long busses
3. Star wiring instead of daisy-chain (causes reflections)
4. Wrong parity - some gateways default to Even, SDM630 defaults to None
5. Cat5/Cat6 cable instead of 120Ω twisted-pair
6. Missing termination on long busses or high baud rates
7. Odd start address or count - float32 registers must be on even addresses
8. CH340 USB-RS485 adapter - use FTDI-based instead
9. Two masters on the same bus - e.g. inverter AND home automation both wanting to read. Doesn't work with standard RS485.
10. Logger interference with ESPHome on hardware UART without logger: baud_rate: 0

SDM630 vs alternatives

Warning about SDM72D-M: It does not count phase-balanced energy ("nicht saldierend"). When L1 exports while L3 imports simultaneously, the SDM72D records both as separate flows. For PV installations with single-phase inverters, this gives wrong numbers - use SDM630 V2+.

Frequently asked questions

Conclusion

The Eastron SDM630 is the default choice for 3-phase Modbus energy monitoring in Europe - and for good reason. ~100 registers, MID certification, 100A direct connection, and a vast ecosystem with native support in Home Assistant, ESPHome, Tasmota, EVCC, SmartEVSE, and virtually every non-proprietary solar inverter.

With the register tables, wiring instructions, and code examples in this guide, you can have a complete energy monitoring setup running in an afternoon. Whether you're tracking a solar installation, billing tenants, or optimizing self-consumption before net metering changes kick in - the SDM630 delivers the data.