The SDM120 CT meter ships with a fixed Modbus ID that can't be changed through the meter itself. Here's how to fix it — and the permanent solution now rolling out.
What’s the Problem
The SDM120 CT meter is widely used with Deye systems for energy monitoring. On installs with more than one meter on the same Modbus bus, each meter needs a unique ID. The SDM120 CT doesn’t allow you to change its Modbus address through any physical buttons or the meter’s own interface — it ships locked to a default ID.
This means installers hit a wall on any job requiring multiple metering points. The system can’t distinguish between two meters with the same address, causing communication failures and incorrect energy data.
Current Workaround
Manual ID Change via Computer
The current fix requires connecting the SDM120 CT to a computer via a USB-to-RS485 adapter and using Modbus configuration software to manually reassign the meter’s ID.
What You Need
USB-to-RS485 converter/adapter
USB-to-RS485 converter/adapter
Computer with Modbus RTU master software (e.g. QModMaster, ModRSsim, or similar)
Process Overview
Connect the SDM120 CT to your computer via the USB-to-RS485 adapter
Open your Modbus software and connect at the meter's default baud rate (9600, 8N1)
Read the current holding register for the Modbus address
Write the new Modbus address to the appropriate register
Power-cycle the meter to confirm the new address has been saved
Verify communication with the Deye inverter at the new address
Not Ideal for Field Work
This requires carrying a laptop and adapter to site, which most sparks don’t do as standard. It’s a valid workaround but adds 15–30 minutes to an install and requires familiarity with Modbus tools. If you’re unsure, call Deye technical support on 02 8529 6809 and we’ll walk you through it live.
Permanent Fix — Now Available
New Meter With Changeable ID
A new meter variant is now in circulation that allows the Modbus ID to be changed directly through the meter’s own interface — no computer or adapter needed.
These meters have been assigned a dedicated part number for tracking purposes. When ordering, request the updated meter variant and we’ll confirm availability.
Ordering
Contact Deye technical support to confirm you’re receiving the updated meter variant with user-changeable ID. We’ve requested a specific part number from the manufacturer to make tracking straightforward — ask for the updated SDM120 CT when placing your order.