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SDM01 Combo

Applies to: SDM01 Combo | Hardware Revision: V1.0+ | Last Updated: 2026-05-13

1. Introduction

The SDM01 Combo Compact Energy Meter is a compact 18mm-wide DIN-rail device for real-time three-phase and multi-branch single-phase monitoring. With three split-core CTs, it precisely measures voltage, current, power, and energy, supporting wired and wireless communication for seamless integration.

Product Highlights

  • Bi-directional Measurement: Measure power and energy flow in both consumption and generation.

  • Easy Installation: The monitoring module requires just 1MW at DIN rail, paired with compact split-core CTs.

  • Local Automation: Enable a wide range of local APIs, ideal for DLB and zero export for Home Energy Management Systems (HEMS).

  • Real-time Monitoring: Monitor key electrical data like Voltage, Current, and Power in real time.

  • Versatile Connectivity: Choose from various communication options such as Wi-Fi, Zigbee, Modbus, etc., catering to diverse system integration needs.

  • Modbus Support: Modbus version & hybrid WiFi/Zigbee+Modbus variants are available for industrial installations.

Typical Application

  • Home energy management systems (HEMS)

  • energy management systems (EMS) for small business

  • Energy management systems (EMS) for buildings, Infrastructure, and Industry

  • Dynamic load balancing (DLB) for electrical vehicle charging

  • Export limitation for renewable power generation

2. Part Description

1

Connector for voltage take-offs connection

The monitor is powered by AC power supply and measures voltage through four cables: X, Y, Z, and N

2

Connector for current transformer connection

The Red (+) and Black (-) wires of CT(X), CT(Y), and CT(Z) must match the corresponding polarity of the connector.

3

Connector for RS485 communication

For Modbus RTU communication

4

Reset button

Press and hold for 3–5 seconds to enter pairing mode.

5

Status LED (ACT)

Indicates device operation and network status through different flashing patterns.

6

Alarm LED (AL)

Flashes to indicate system alarms or errors.

7

Product QR code

Contains manufacturing batch information.

8

Product model

See “Ordering Information” section for product selection

9

Locking clip for DIN rail mounting

Mounts onto a 35mm DIN rail.

10

Calibration ID

The calibration ID on the split-core CT must match the one on the monitor for optimal accuracy.

11

Split-core CT locking clasp

Ensure the clasp is securely locked for precise measurement.

12

Positive power flow direction

Indicates positive power flow direction for CT(X), CT(Y), and CT(Z) installation.

3. Technical Data

Rated operating voltage Un

~220-240 VAC phase to neutral, 50/60 Hz ~380-415 VAC phase to phase, 50/60 Hz1)

Max current Imax

120A / 200A

Over-voltage category

III

Rated insolating voltage Ui

440V

Rated impulse withstand voltage Uimp

4kV

Pollution degree

3

Protection degree

IP20

Energy measurement accuracy

Class 1 (IEC 61557-12)

Maximum Power consumption

≤ 2VA

Rated operating temperature

-25℃ to 55℃

Main module dimension

113.7×18.0×65.9mm

Clamp CT apertures

Ø16mm / Ø20mm

Communication Type

Wireless2): BLE; Wi-Fi; Zigbee Wired: RS485

Remark: 1) Not suitable for 3P3W installation.

2) Four variants of main module available with different connectivity - Tuya WiFI (SDM01-TWM-*), Tuya Zigbee (SDM01-TZM-*), Open WiFI (SDM01-EWM-*), Standard Zigbee 3.0 (SDM01-TZM-*-U01)

4. Mechanical Outline

  • Dimension: Unit in mm

  • Main Unit: Monitoring module for DIN-rail installation (18mm width)

  • Split-core Current Transformer - 120A (CT Clamp - 120A):

  • Split-core Current Transformer - 200A (CT Clamp - 200A):

5. Electrical Installation

Wiring Diagram

⚠️ Safety Remarks:

  • The device must be associated with easily accessible upstream protective devices ‒ such as miniature circuit breakers (MCB).

  • The device must be installed, operated, serviced, and maintained ONLY by qualified professionals.

  • Please read the user guide carefully before installation for detailed wiring diagrams and safety precautions.

Three-phase (3P4W) System Wiring

Single-phase System Wiring up to 3 Branch Circuits

Note: Naming conventions for three-phase systems vary by region (e.g., L1, L2, L3 in Europe vs. A, B, C in China). Additionally, this product supports monitoring three independent branch circuits in a single-phase system. Therefore, the terminals are universally labeled as Lx, Ly, and Lz.

Installation Video

6. User Interface

Reset Button

Press and hold for 3–5 seconds to enter pairing mode.

LED Indicator

Cover

Solid ON

Device connected - the device is online and functioning normally with cloud connectivity.

Cover

Flashing at 2Hz

Pairing mode – press and hold the reset button until the LED flashes rapidly.

Cover

Flashing at 0.5Hz

Reconnecting to network - the device is attempting to reconnect using saved network settings.

Cover

Flashing at 1Hz

Network connected, cloud unreachable - the device is connected to Wi-Fi/Zigbee, but failed to reach the cloud.

Cover

Flashing at 0.25Hz

The device failed internal self-check. Please power off, restart, and reconfigure the network settings.

Cover

Flashing at 1Hz

Alarm reminder - The device has detected a fault. Please check the wiring and power supply.

Cover

Solid ON

Device connected - the device is online and functioning normally with cloud connectivity.

Cover

Flashing at 2Hz

Pairing mode – press and hold the reset button until the LED flashes rapidly.

Cover

Flashing at 0.5Hz

Reconnecting to network - the device is attempting to reconnect using saved network settings.

Cover

Flashing at 1Hz

Network connected, cloud unreachable - the device is connected to Wi-Fi/Zigbee, but failed to reach the cloud.

Cover

Flashing at 0.25Hz

The device failed internal self-check. Please power off, restart, and reconfigure the network settings.

Cover

Flashing at 1Hz

Alarm reminder - The device has detected a fault. Please check the wiring and power supply.

Cover

Solid ON

Zigbee connected, BLE disconnected – the device is connected to a Zigbee network while BLE is turned off or not connected.

Cover

Flashing at 2Hz

Pairing mode – press and hold the reset button until the LED flashes rapidly.

Cover

Flashing at 0.5Hz

Reconnecting to network - the device is attempting to reconnect both BLE (if available) and Zigbee using saved settings.

Cover

Flashing at 1Hz

BLE connected(if available) - the LED flashes at 1Hz whenever BLE is connected, regardless of Zigbee status.

Cover

Flashing at 0.25Hz

The device failed internal self-check. Please power off, restart, and reconfigure the network settings.

Cover

Flashing at 1Hz

The device has detected a fault. Please check the wiring and power supply.

Cover

Solid ON

Wi-Fi connected, BLE disconnected - the device is connected to Wi-Fi while BLE is disconnected.

Cover

Flashing at 2Hz

Pairing mode – press and hold the reset button until the LED flashes rapidly.

Cover

Flashing at 0.5Hz

Reconnecting to network - the device is attempting to reconnect both BLE and Wi-Fi using saved settings.

Cover

Flashing at 1Hz

BLE connected - the LED flashes at 1Hz whenever BLE is connected, regardless of Wi-Fi status.

Cover

Flashing at 0.25Hz

The device failed internal self-check. Please power off, restart, and reconfigure the network settings.

Cover

Flashing at 1Hz

Alarm reminder - The device has detected a fault. Please check the wiring and power supply.

7. System Integration

Wireless communication

Products equipped with different communication SoC firmwares connect to different systems and cloud platforms. Users can select the appropriate version based on their specific application requirements.

The Tuya WiFi version can only be integrated into the Tuya Cloud using Tuya's encrypted MQTT communication. It cannot be directly integrated with any third-party cloud platforms, ecosystems, or gateways. Third-party clouds or edge gateways need to be integrated via Tuya cloud APIs. For details, please refer to Tuya's developer documentation.

Note:

  1. Tuya's strategy for adjusting the cloud data reporting frequency is not fully disclosed. Based on the latest updates as of April 2026, provided the daily data reporting traffic limit is not exceeded, the fastest expected reporting interval will be between 5 to 15 minutes.

  2. Tuya's Smart Life App is user-friendly and straightforward, making it ideal for entry-level smart home users who prefer simplicity and basic energy consumption monitoring.

For standard operation, the Tuya Zigbee version must be integrated with a Tuya gateway, which then connects to the Tuya Cloud via Tuya's encrypted MQTT communication.

Note:

  1. Tuya's strategy for adjusting the cloud data reporting frequency is not fully disclosed. Based on the latest updates as of April 2026, provided the daily data reporting traffic limit is not exceeded, the fastest expected reporting interval will be between 5 to 15 minutes.

  2. There are unofficial methods available on the market to integrate Tuya Zigbee products with third-party gateways or hubs - such as Home Assistant integration via Zigbee2MQTT. However, please be aware of the following potential issues when using these unofficial integration methods:

  • ⚠️Network Congestion: Tuya's proprietary Zigbee data transmission strategy does not bundle data packets. Consequently, high-frequency reporting of the extensive electrical data types from several energy meters, which generate significantly more data than typical smart home Zigbee devices, can easily cause Zigbee network congestion.

  • ⚠️Security Risks: Integrating with third-party Zigbee gateways using the default global Trust Centre Link Key “ZigbeeAlliance09” poses potential information security risks. Therefore, using non-Tuya gateways in commercial projects is highly discouraged. For third-party gateway integration, the Standard Zigbee 3.0 version with Install Code is strongly recommended.

The Standard Zigbee 3.0 version can seamlessly connects to third-party gateways. Thanks to the standardized application-layer integration of Zigbee 3.0, it is highly convenient and widely applicable for both residential and commercial building projects.

Currently supported smart home ecosystems include:

  • Home Assistant: Integration via Zigbee2MQTT (SPM01, SPM02, SDM01, and SDM02)

  • SmartThings: Integration via the SmartThings Hub driver (officially approved).

  • Homey: Integration via the Bituo Technik App

You can find information about the commonly used Zigbee Cluster Library on this page.

The Open Wi-Fi version of SDM01 provides the following open APIs (refer to the Device API document), enabling users to implement local automation and connect to custom cloud platforms.

  1. Zero-Configuration Discovery Mechanism (LAN Addressing)

    • mDNS / DNS-SD: Supports automatic discovery of the energy meter by EV chargers and PV inverters on the Local Area Network (LAN) without the need for IP scanning.

  2. BLE Near-Field Communication Mode (Offline/Maintenance)

    • BLE GATT (Time-limited activation): Requires PIN code + PAKE algorithm authentication for local high-privilege configuration and network resets. Wakes up on demand and closes upon timeout.

    • BLE Broadcast (Always-on 24/7): Unidirectional broadcast of AES-encrypted real-time power data, allowing nearby low-power devices to listen with zero latency and without requiring a connection.

  3. LAN Standard Mode (Ultra-low Latency Device Communication) Plaintext or lightweight encryption for local networks.

    • Modbus TCP: Used for local linkage with EV chargers and PV inverters.

    • Local MQTT: Used for local integration with open-source smart home ecosystems.

    • WebSocket (WS) / Raw UDP: Ultra-high frequency real-time power streaming subscription (enables DLB completion within 1-2 seconds).

    • HTTP / CoAP: Suitable for low-frequency parameter configuration and status queries.

  4. Cloud Device Access Layer (Device-to-Cloud / Southbound API)

    • MQTTS (MQTT over TLS 1.2/1.3): Core main communication link.

    • HTTPS (OTA dedicated): Exclusively used for downloading large Over-The-Air (OTA) firmware upgrade packages.

Wired communication

SDM01 provides a Modbus RTU over RS485 interface, making it convenient to use as a wired Modbus RTU meter. You can view the Modbus RTU register address information by clicking the page below.

SDM01 Modbus RTU Map

8. Ordering Information

#
Ordering number
Description

1

SDM01-TWM-12

SDM01 SCTA-3×120A/Φ16 Wi-Fi (Tuya)+RS485

2

SDM01-TWM-20

SDM01 SCTA-3×200A/Φ20 Wi-Fi (Tuya)+RS485

3

SDM01-TWM-12TS

SDM01 SCTA-3×120A/Φ16 Wi-Fi (Tuya LAN+)+RS485

4

SDM01-TWM-20TS

SDM01 SCTA-3×200A/Φ20 Wi-Fi (Tuya LAN+)+RS485

1) Tuya LAN+: Tuya LAN+ is a specific Wi-Fi SoC firmware provided by Tuya Smart that features local area network (LAN) communication. It is suitable for local LAN communication with products such as EV chargers, microinverters, and micro-energy storage systems that are also equipped with Tuya LAN+ communication firmware. This model can only be purchased through Tuya's official or designated channels.

#
Ordering number
Description

1

SDM01-TZM-12

SDM01 SCTA-3×120A/Φ16 Zigbee (Tuya)+RS485

2

SDM01-TZM-20

SDM01 SCTA-3×200A/Φ20 Zigbee (Tuya)+RS485

#
Ordering number
Description

1

SDM01-TZM-12-U01

SDM01 SCTA-3×120A/Φ16 Zigbee (Std. ZB3.0)+RS485

2

SDM01-TZM-20-U01

SDM01 SCTA-3×200A/Φ20 Zigbee (Std. ZB3.0)+RS485

#
Ordering number
Description

1

SDM01-EWM-12

SDM01 SCTA-3×120A/Φ16 Wi-Fi (ESP-8685)+RS485

2

SDM01-EWM-20

SDM01 SCTA-3×200A/Φ20 Wi-Fi (ESP-8685)+RS485

9. FAQ

FAQ

10. Troubleshooting

Troubleshooting

11. Printed Document

Document
Download

Datasheet

⬇️ PDF

User Guide

⬇️ PDF

12. Explore More

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