> For the complete documentation index, see [llms.txt](https://docs.bituo-technik.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bituo-technik.com/product-document/sdm-series.md).

# SDM Series

## SDM Series — Compact Energy Meters with Clamp CTs

Future-ready smart energy meters with split-core clamp CTs, designed for DIN rail installation. Supports three-phase, split-phase, and multi-branch single-phase monitoring — engineered for both IEC and UL markets.

<figure><img src="https://68488808-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTmsWivaZjkubbVKrCezC%2Fuploads%2Fazc1ZJIySptoUxzRFM9K%2Fimgi_9_SDM-Family_3%20(1).webp?alt=media&amp;token=fd9fe6e1-4c29-4a49-829f-b8d4376402c8" alt=""><figcaption></figcaption></figure>

***

### Product Variants

SDM products are defined across **three dimensions**:

#### 1. Product Platform

|                            | **SDM01 Combo**                                 | **SDM02 SP**                          |
| -------------------------- | ----------------------------------------------- | ------------------------------------- |
| **Target System**          | Three-phase (3P4W) or multi-branch single-phase | Split-phase / two-phase               |
| **Market**                 | IEC (EU, Asia, etc.)                            | IEC + UL (North America)              |
| **Rated Voltage**          | 220–240 VAC (L-N) / 380–415 VAC (L-L)           | 110–240 VAC (L-N) / 220–240 VAC (L-L) |
| **No. of CTs**             | 3× split-core CTs                               | 2× split-core CTs                     |
| **Dimension**              | 113.7 × 18.0 × 65.9 mm (1MW DIN rail)           | 42.2 × 41.6 × 20 mm                   |
| **Wired Communication**    | RS485 (Modbus RTU)                              | —                                     |
| **Active Energy Accuracy** | Class 1 (IEC 61557-12)                          | Class 1 (IEC 61557-12)                |

#### 2. CT Current Rating

| CT Rating         | Aperture | SDM01 Combo | SDM02 SP          |
| ----------------- | -------- | ----------- | ----------------- |
| **120A**          | Ø16 mm   | ✅           | ✅                 |
| **200A**          | Ø20 mm   | ✅           | ✅                 |
| **100A (UL2808)** | Ø12 mm   | —           | ✅ (North America) |

> 💡 The CT is factory-calibrated together with the main module. Always order the CT rating that matches your installation — CTs are **not interchangeable** between ratings.

> ℹ️ Current monitoring can be extended up to **400A** via custom CT configurations. Please contact us for customization inquiries.

#### 3. Connectivity

**Wireless** — select one firmware variant per order:

<table><thead><tr><th width="116">Variant</th><th width="137">Communication</th><th width="235">Archetecture</th><th>API Style</th><th width="140">Typical Users</th></tr></thead><tbody><tr><td><strong>Tuya Wi-Fi</strong> (<code>*TW</code>)</td><td>Wi-Fi</td><td>BK7231N SoC (Tuya Firmware, Slave) + Metering MCU (Bituo Firmware, Master)</td><td>MQTT(Tuya Proprietary)</td><td>Tuya ecosystem, IoT beginners</td></tr><tr><td><strong>Tuya Zigbee</strong> (<code>*TZ</code>)</td><td>Zigbee</td><td>EFR32MG21 SoC (Tuya Firmware, Slave) + Metering MCU (Bituo Firmware, Master)</td><td>Tuya Proprietary Clusters</td><td>Tuya ecosystem with Zigbee hub</td></tr><tr><td><strong>Open Wi-Fi</strong> (<code>*EW</code>)</td><td>BLE + Wi-Fi</td><td>ESP8685 SoC (Bituo Firmware, Master) + Metering MCU (Bituo Firmware, Slave)</td><td>MQTT, HTTP, UDP, BLE</td><td>DIYers, System Integrators</td></tr><tr><td><strong>Std. Zigbee</strong> (<code>*TZ-U01</code>)</td><td>Zigbee 3.0</td><td>EFR32MG21 SoC (Bituo Firmware, Master) + Metering MCU (Bituo Firmware, Slave)</td><td>Standard Zigbee 3.0 Clusters</td><td>System Integrators, DIYers</td></tr></tbody></table>

**Wired** — availability by platform:

|                        | **SDM01 Combo**            | **SDM02 SP** |
| ---------------------- | -------------------------- | ------------ |
| **RS485 (Modbus RTU)** | ✅ Included in all variants | —            |

> ℹ️ On SDM01 Combo, RS485 is always present alongside the wireless module — it is not a separate variant choice.

***

### Sub Pages

<table><thead><tr><th width="194">Model</th><th>Description</th></tr></thead><tbody><tr><td><a data-mention href="/product-document/sdm-series/sdm01-combo.md">SDM01 Combo</a></td><td>3PN / Multi-branch 1P, 120A or 200A</td></tr><tr><td><a data-mention href="/product-document/sdm-series/sdm02-sp.md">SDM02 SP</a></td><td>Split-phase / 2×1P+N, 120A / 200A / 100A (UL)</td></tr></tbody></table>

***

### Related

[SPM/SDM Zigbee Cluster Reference](/device-api/spm-sdm-zigbee-cluster-reference.md)

[SDM01 Modbus RTU Map](/device-api/sdm01-modbus-rtu-map.md)