Device Overview
Eastron SDM120CTM is a 1-module, CT-operated single-phase multi-function energy meter with RS485 Modbus RTU and pulse outputs. It is intended for single-phase AC systems where the monitored current is measured through external current transformers instead of directly through the meter body.
Core Characteristics
The meter measures active energy, reactive energy, current, voltage, power, power factor, frequency, and demand. Eastron positions the SDM120CT family for residential, solar PV, industrial, and utility energy monitoring, with bidirectional energy measurement that makes it useful for import/export visibility when CT placement and monitoring software are configured correctly.
Installation And Measurement
SDM120CTM is a 1-module, 18 mm wide DIN-rail meter for 1P+N / 1P2W systems at 230 V nominal voltage. It uses external CTs with 1 A or 5 A secondary input, and the CT primary can be configured from 1 A to 9999 A. That CT-operated format matters where a direct-connected single-phase meter is not the right fit.
Communication And Integration
The Modbus model provides RS485 Modbus RTU plus two pulse outputs. Core metering is local and does not require a vendor cloud. Home Assistant use should be treated as a standards-based Modbus integration route through compatible RS485 hardware, not as an Eastron-native app integration.
Fit And Limits
This is a good fit for single-phase panels, PV import/export monitoring, and sub-metering projects that need a narrow DIN-rail device and local data access. It is not a battery, EV charger, solar inverter, or gateway-only product. The 9999 A comparison value represents the configurable CT primary range, not current carried directly through the meter.