Read voltage, current, power, power factor, frequency and energy from an Eastron SDM630 three-phase energy meter over Modbus RTU. This guide gives the full register map, FLOAT32 decoding, the FC04 input-register detail that trips people up, and how to get live data — and log it — with ModbusManager on Windows.
Windows 10/11 · free 14-day Pro trial · open the .json workspace inside the app
The SDM630 register layout is so widely used that other meters clone it — learn it once and you can read many devices.
Eastron’s SDM630 is the most widely deployed three-phase Modbus energy meter in the European prosumer and installer market — MID-certified, direct 100 A connection (or CT version), and around 100 Modbus registers covering everything from per-phase voltage to total energy. Its register map has become the de facto reference: the SDM630MCT and SDM630-TCP variants share it, and many Carlo Gavazzi and clone meters follow the same FLOAT32 layout. If you can read an SDM630, you can read most three-phase Modbus meters.
A free ModbusManager Pro workspace with the SDM630 register map already set up: Float32 tags and an energy-meter dashboard. Open it and point it at your meter.
The workspace polls input registers from 30001 (FC04) and decodes voltage, current, power, power factor and frequency as 32-bit floats — no scripting, no manual word-pairing. Every value lands on a clean dashboard ready to read. Set your meter’s slave ID and connection, and you have live data in seconds.
Open in ModbusManager Pro · 📋 Workspace → open · needs the Float32 tag type (v1.6+)
Set these from the meter’s front panel (SET menu), then match them in ModbusManager.
| Setting | Typical value |
|---|---|
| Protocol | Modbus RTU (2-wire RS-485) |
| Baud rate | 9600 (also 2400/4800/19200/38400) |
| Parity | None (1 stop bit) — default |
| Node address | 1–247 (set on meter) |
| Function code (measurements) | 04 — input registers |
| Function code (config) | 03 read / 16 write — holding registers |
| Data type | FLOAT32 (2 registers, big-endian) |
Baud rate is not only a setup detail — it caps how often a whole line of meters can be read. At 9600 baud a 10-register read of one SDM630 costs roughly 52 ms, so twenty meters on the same pair need about a second for one full pass. See for the timing per baud rate and how to pick an interval that holds.
All values are FLOAT32 (two registers each), read with function code 04. Addresses use the 1-based 30001 input-register numbering from the Eastron protocol.
| Register | Measurement | Unit | Type |
|---|---|---|---|
| 30001 | Voltage L1-N | V | FLOAT32 |
| 30003 | Voltage L2-N | V | FLOAT32 |
| 30005 | Voltage L3-N | V | FLOAT32 |
| 30007 | Current L1 | A | FLOAT32 |
| 30009 | Current L2 | A | FLOAT32 |
| 30011 | Current L3 | A | FLOAT32 |
| 30013 | Active Power L1 | W | FLOAT32 |
| 30015 | Active Power L2 | W | FLOAT32 |
| 30017 | Active Power L3 | W | FLOAT32 |
| 30053 | Total Active Power | W | FLOAT32 |
| 30071 | Total Power Factor | — | FLOAT32 |
| 30077 | Frequency | Hz | FLOAT32 |
| 30073 | Total Import Active Energy | kWh | FLOAT32 |
| 30075 | Total Export Active Energy | kWh | FLOAT32 |
The SDM630 exposes around 100 registers in total, including per-phase apparent and reactive power, per-phase power factor, THD and demand values. The full list is in the Eastron SDM630 Modbus protocol document; the registers above are the most commonly polled.
The SDM630MCT measures through external current transformers instead of direct connection, but speaks the same Modbus: FC04, FLOAT32 pairs, and the measurement addresses above are identical. The practical differences are the CT ratio — set from the meter’s set-up menu (or the holding registers listed in the MCT protocol document) so the reported currents and powers are already scaled to primary values — and slightly different energy-resolution behaviour on some firmware. If your SDM630MCT readings look off by a constant factor, the CT ratio is the first thing to check. The free workspace on this page works with the MCT unchanged.
From wiring to live values in a few minutes.
ModbusManager reads any SDM630 register directly, with built-in FLOAT32 decoding so you do not combine register pairs by hand, and a serial monitor to see every frame. The Standard edition ($49) covers polling, scaling and the serial monitor. The Pro edition ($119) adds drag-and-drop Modbus HMI software, a data logging Historian with CSV export for energy and load profiling, and an alarm system — all running locally on Windows, with no SCADA server or cloud account.
One SDM630 is easy. Ten of them on the same RS-485 line, read by a PLC that has a single Modbus connection, is a different job. ModbusManager Pro can poll every meter and republish just the values you need — total active power, per-phase currents, energy counters — as one common register map the PLC reads in a single request. The FLOAT32 pairs stay floats, or get scaled into integers if that is what the PLC block expects.
Modbus gateway software →Download ModbusManager and connect to your meter over RTU. Free 14-day Pro trial — no credit card, no cloud.
Windows 10/11 · Standard $49 · Pro $119 one-time
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