Decoding data from the Eastron SDM320-LoRa
Identifying your meter
The Eastron SDM320-LoRa is a single phase DIN rail mounted electricity meter that communicates over LoRaWAN. As illustrated by the image (left) below it will say SDM320C directly to the right of the Eastron logo. The Serial Number (SN) is located on top, above the display as displayed in the image (right).
Connecting your meter to a LoRaWAN Network Server
The SDM320-LoRa can be connected to any LoRaWAN Network Server (LNS) including TTN, TTI, Chirpstack and Loriot amongst others. cThings Cloud provide an end-to-end in-built LNS with pre-configured decoders to facilitate connecting the SDM320-LoRa to your existing system. Contact us to find out more.
Decoding the default data received from the SDM530-LoRa
All SDM320-LoRa meters come with a default configuration pre-installed. If a custom configuration has been requested, see the section below on custom configurations.
By default, data will be sent from the SDM320-LoRa every 30 minutes. Below is an example hex encoded payload that could be sent from a default configured meter (it has been conveniently separated into chunks to match the decode in the table below).
The meter will send the data in a single payload with the 5 default parameters. The below table shows how to decode the payload and parameters.
Byte Range | Description | Data Type | Example Hex | Decoded |
|---|---|---|---|---|
0-3 | Serial Number | UINT32 | 0EEC3B41 | 250362689 |
4 | Message Fragment Number (always 1 for default configuration) | UINT8 | 01 | 1 |
5 | Number of Parameter Bytes in this Payload (always 20 for default configuration) | UINT8 | 14 | 20 |
6-9 | Total kWh | FLOAT | 4343774C | 745.036 |
10-13 | Relay state | FLOAT | 000000FF | Relay active |
14-17 | Digital input state | FLOAT | 00000000 | False |
18-21 | Active Power | FLOAT | 44C4A732 | 1573.225 |
22-25 | Current | FLOAT | 42C5DA1D | 6.59009743 |
26-27 | Modbus Checksum |
| 77C4 |
|
Custom Configurations
Your SDM320-LoRa may have been configured to send different parameters in a different order. If this is the case, you should have received more information about your custom configuration when you ordered your meter.
Advanced Decoding
Decoding the Relay State
The command 01 03 fc b0 00 01 b5 bd returns the Relay State at position 0 (XX YY) and the DI State at position 1 (XX YY) where the following value mappings exist.
Value | DI State | Relay State |
|---|---|---|
00 00 | FALSE | Supply Inactive |
00 FF | FALSE | Supply Active |
FF 00 | TRUE | Supply Inactive |
FF FF | TRUE | Supply Active |
Fragmentation
By default, the SDM320-LoRa will send 5 parameters in a single payload (one message fragment). For non-standard configurations more parameters may be sent in which case the payload may be fragmented across multiple LoRaWAN payloads. Each parameter will always be 4 bytes in length, starting from byte 6 (0-based) and the final 2 bytes of the message will always be a 2 byte Modbus Checksum.
Updated on: 18/03/2026
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