The SPM‑Main communicates with the cloud via LAN (Ethernet) or Wi‑Fi, and with SPM‑4Relay switches via RS‑485. You get reliable transmission over longer distances without dropouts.
One SPM‑Main controls up to 32 SPM‑4Relay modules, each with 4 channels (20 A per channel). Ideal for apartment buildings, offices, or retail with multiple consumption points.
Accurate consumption metering with up to 180 days of history on an SD card (8–32 GB, SDHC). Easily view and export data in the eWeLink app.
SONOFF SPM‑Main is a robust main module of the Smart Stackable Power Meter system for apartment buildings, offices, server rooms, and retail. It allows scaling to 128 independent channels (up to 32× SPM‑4Relay), with each channel handling loads up to 20 A. Cloud connectivity via Ethernet or Wi‑Fi and RS‑485 bus communication ensure stable transmission over long distances.
Safety is prioritized with overload protection, configurable current/voltage/power thresholds, and a load delay function. The SD card slot (8–32 GB, SDHC) enables storing and exporting up to 180 days of measurement history directly from the eWeLink app—keeping your consumption fully under control from anywhere.
Main benefits:
- Precise real-time energy consumption metering in the eWeLink app
- LAN and Wi‑Fi cloud connectivity for reliable monitoring
- Expandable up to 128 channels (SPM‑4Relay)
- RS‑485 for stable long-distance communication
- Overload protection for safe operation
- DIN-rail mounting and easy installation
- History storage on SD card and easy data export
