SDM120 Modbus Library

This is an Arduino Library for the multi-functional energy meter SDM120 Modbus.

Index

• Pre-requisite
• Installation
  • Windows
  • Linux
• How-to
  • Convert Float to Array of Bytes (IEEE 754)
  • Convert Array of Bytes to Float (IEEE 754)
  • Construct Commands
  • Get Raw Data from SDM120 Modbus
  • Get all Processed Data from SDM120 Modbus
• Error Codes
• Bugs Reporting
• TODO

Pre-requisite

• Installed the lastest version of Arduino
• git

Installation

Windows

• Open cmd, enter

cd %userprofile%\Documents\Arduino\libraries &&
git clone https://github.com/ngharry/SDM120-Modbus

to download SDM120 Modbus library.

• Wait until the downloading process finishes.

Linux

[TODO] Add tutorial for Linux here.

How to

Convert Float to Array of Bytes (IEEE 754)

See examples/FloatToBytes.

Convert Array of Bytes to Float (IEEE 754)

See examples/BytesToFloat.

Construct Commands

See examples/ConstructCommands.

Get Raw Data from SDM120 Modbus

See examples/GetRawData.

Get all Processed Data from SDM120 Modbus

See examples/GetData.

Error Codes

HEX	DEC	Name	Description
0x00	0	STATUS_ERROR	General errors
0x01	1	STATUS_SUCCESS	Function runs successfully, no errors
0x02	2	ERR_READ_RS485	No data read from RS485 communication
0xFA	250	ERR_FUNC	Unrecognised function sent to SDM120

Bugs Reporting

TODO

• Add terminology table.
• Add more error codes (as specified in doc/SDM120 PROTOCOL.pdf).
• Add intalling process for Linux (I love Linux).