The Microcare SDM630 is a three-phase multifunction energy meter mounted on a DIN rail, used for sub-billing, grid monitoring, and PV system measurement. This Modbus RTU template reads per-phase reactive power on L1, L2, and L3, plus total system current, total active power, total reactive power, grid frequency, and cumulative reactive energy in both import and export directions. Connecting it through the ModbusCloud Gateway gives installers a continuous record of power quality and energy flows without manual meter reads.
Use cases
Monitor total active power in real time to detect unexpected load increases across three-phase circuits.
Track cumulative reactive consumption and production energy to verify power factor correction equipment performance.
Alert on grid frequency deviations to identify supply quality issues before they affect sensitive equipment.
Compare per-phase reactive power on L1, L2, and L3 to spot phase imbalance in commercial installations.
Report total system current over time to verify that installed cable ratings are not being exceeded.
Installation
1Confirm that your SDM630 unit is the Modbus version: check the front label for 'Modbus' or 'RS485', then set the Modbus address (default 1) and baud rate (default 9600) using the front-panel buttons under the communication settings menu.
2Wire the RS485 A and B terminals of the SDM630 to the corresponding A and B terminals on the ModbusCloud Gateway using a shielded twisted-pair cable; add a 120-ohm termination resistor at each end of the bus if the meter is the last device on the line.
3In the ModbusCloud portal, add a new gateway, import the Microcare SDM630 template, and assign the Modbus unit ID that matches the address configured on the meter front panel.
4Spot-check the connection by opening the live register view in the portal and confirming that the frequency register reads approximately 50 Hz and total active power reflects the known load on the circuit.
Things to watch for
01
All register values read zero or NaN. What is wrong?
The SDM630 returns all values as 32-bit IEEE 754 floats spread across two consecutive 16-bit registers. Requests must start on an even address and request an even number of registers. If your gateway polls a single 16-bit register instead of a pair, every reading will be corrupt. Confirm the template uses FC4 with register-pair requests.
02
The gateway connects but phase reactive-power values look wrong.
The SDM630 sends the most significant register first by default, but this word order can be auto-reversed by the firmware. Verify that your ModbusCloud Gateway and the meter agree on big-endian (high word first) byte order. A byte-swapped float32 will produce a nonsensical large or near-zero value rather than an obvious error.
03
No Modbus response at all, even though wiring looks correct.
Check that baud rate, parity, and stop-bit settings on the SDM630 front panel match those configured in the ModbusCloud Gateway. The meter supports 2400, 4800, 9600, 19200, and 38400 baud; the factory default is 9600 8N1. A single mismatch will prevent any response. Also verify the RS485 A/B polarity is not reversed.
04
Readings are intermittent on a bus with several meters.
The SDM630 protocol documentation states that each request must be limited to 40 parameters or fewer. If the gateway sends one large block read covering too many registers in a single request, the meter returns a Modbus exception and drops the poll. Split polls into smaller requests, and ensure each meter on the bus has a unique address between 1 and 247.
Registers (9)
9 read / 0 write
Name
Address
Function
Type
Unit
Access
reactive_power_l1
Reactive power on phase 1, volt-amperes reactive.
24
FC04
float32
W
R
reactive_power_l2
Reactive power on phase 2, volt-amperes reactive.
26
FC04
float32
W
R
reactive_power_l3
Reactive power on phase 3, volt-amperes reactive.
28
FC04
float32
W
R
current
Total system current, sum of all phase currents.
48
FC04
float32
A
R
active_power
Total system active power across all phases.
52
FC04
float32
W
R
reactive_power
Total system reactive power, volt-amperes reactive.
60
FC04
float32
var
R
frequency
AC supply frequency, hertz, typically 50 or 60.
70
FC04
float32
Hz
R
reactive_production_energy
Cumulative reactive energy exported to the grid.
76
FC04
float32
Wh
R
reactive_consumption_energy
Cumulative reactive energy imported from the grid.
78
FC04
float32
Wh
R
Working with Modbus in your projects?
ModbusCloud is the hardware-plus-software platform that installers use to monitor, visualise and control Modbus devices from one portal. This template is one of hundreds you can use right away.
