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Eastron SDM120CT-M Modbus register map

Also searched as: SDM120CT · SDM120CTM · SDM120CT-Modbus · SDM120CT-MOD

35 Modbus registers of the Eastron SDM120CT-M, with the address on the wire, the 30001-style reference, data type, byte order, unit and scale. Transcribed from Eastron SDM120CTM Smart Meter Modbus Protocol Implementation (V1.3).

Single-phase CT-connected DIN-rail energy meter with RS485 Modbus RTU; every value is a 32-bit float.

Registers Read it by name
Device type
Energy meter
Registers
35
Interfaces
Modbus RTU
Default unit ID
1
Byte order (multi-register values)
ABCD
Serial settings
2400 baud, 8 data bits, no parity, 1 stop bit

Hardware verification

Not yet verified on hardware. The map is transcribed from the vendor document and checked against it by script; check the first readings against the device display.

Verify it on your device What the levels mean

Connection notes

  • Read and write floats in register pairs; an odd start address or count returns an exception.
  • Broadcast (address 0) is not supported.
  • The example frame reads 43 66 33 34 as 230.2 V, high word first.
  • Write holding registers with function 16 (10h).
  • The SDM120CT-M 40 mA variant uses a different protocol document; check yours before relying on this map.

Registers

Grouped as in the vendor document.

Voltage 2 registers
Name and key Reference Address Type Byte order Unit Scale
Voltagevoltage 30001 0x0000 float32 ABCD V
Frequencyfrequency 30071 0x0046 float32 ABCD Hz
Current 1 registers
Name and key Reference Address Type Byte order Unit Scale
Currentcurrent 30007 0x0006 float32 ABCD A
Power 4 registers
Name and key Reference Address Type Byte order Unit Scale
Active poweractive_power 30013 0x000C float32 ABCD W
Apparent powerapparent_power 30019 0x0012 float32 ABCD VA
Reactive powerreactive_power 30025 0x0018 float32 ABCD var
Power factorpower_factor 30031 0x001E float32 ABCD
Energy 6 registers
Name and key Reference Address Type Byte order Unit Scale
Import active energyimport_active_energy 30073 0x0048 float32 ABCD kWh
Export active energyexport_active_energy 30075 0x004A float32 ABCD kWh
Import reactive energyimport_reactive_energy 30077 0x004C float32 ABCD kvarh
Export reactive energyexport_reactive_energy 30079 0x004E float32 ABCD kvarh
Total active energytotal_active_energy 30343 0x0156 float32 ABCD kWh
Total reactive energytotal_reactive_energy 30345 0x0158 float32 ABCD kvarh
Demand 8 registers
Name and key Reference Address Type Byte order Unit Scale
Total system power demandactive_power_demand 30085 0x0054 float32 ABCD W
Maximum total system power demandactive_power_demand_max 30087 0x0056 float32 ABCD W
Import system power demandimport_power_demand 30089 0x0058 float32 ABCD W
Maximum import system power demandimport_power_demand_max 30091 0x005A float32 ABCD W
Export system power demandexport_power_demand 30093 0x005C float32 ABCD W
Maximum export system power demandexport_power_demand_max 30095 0x005E float32 ABCD W
Current demandcurrent_demand 30259 0x0102 float32 ABCD A
Maximum current demandcurrent_demand_max 30265 0x0108 float32 ABCD A
Setup 14 registers
Name and key Reference Address Type Byte order Unit Scale
Demand timedemand_time 40001 0x0000 float32 ABCD min
Demand perioddemand_period 40003 0x0002 float32 ABCD min
Relay pulse widthpulse_width 40013 0x000C float32 ABCD ms
Network parity and stop bitsparity_stop 40019 0x0012 float32 ABCD
Meter ID (Modbus address)modbus_address 40021 0x0014 float32 ABCD
Network baud ratebaud_rate 40029 0x001C float32 ABCD
CT primary currentct_primary 40051 0x0032 float32 ABCD A
CT secondary currentct_secondary 40053 0x0034 float32 ABCD A
Pulse 1 output modepulse1_energy_type 40087 0x0056 float32 ABCD
Reset historical datareset_demand 461457 0xF010 uint16
Scroll display timescroll_time 463745 0xF900 raw s
Pulse 1 output constantpulse1_constant 463761 0xF910 uint16
Measurement modemeasurement_mode 463777 0xF920 uint16
Serial numberserial_number 464513 0xFC00 uint32 ABCD

Source documents

View this map on GitHub (YAML)

Read it by name

Read the SDM120CT-M with an AI assistant

The Proxus Industrial MCP Server includes this map. Set it on the device, and Claude, Cursor or VS Code reads registers by key with the right type, byte order, scale and unit. It only reads.

This device speaks Modbus RTU: reach it through a Modbus TCP gateway and use the gateway’s address with the device’s unit ID.

Get the MCP server

proxus-mcp.json

{
  "devices": {
    "sdm120ct-1": {
      "protocol": "modbus-tcp",
      "host": "192.168.10.40",
      "unit_id": 1,
      "map": "eastron/sdm120ct-m"
    }
  }
}

Ask your assistant

Read voltage, frequency, current from sdm120ct-1.

The tool call it makes

read_named(device: "sdm120ct-1", keys: ["voltage", "frequency", "current"])

Have this device? Verify the map.

Ask your assistant to run verify_device_map. It reads every register once, read-only, checks that the values are plausible and asks you to compare two values with the display. You get a report and a prefilled GitHub issue to submit; your name goes on this map’s verified list.

How verification works

Collecting from many devices?

Proxus reads Modbus TCP and RTU devices next to the machines, keeps the history and delivers the values to dashboards, databases and AI.

Modbus in Proxus Industrial connectivity

Data: Modbus Register Maps by Proxus contributors, CC BY 4.0.