Sdm630 Modbus Register 4: Device name L3 Voltage

Technical Definition

The register device name L3 Voltage at address 4 is used to monitor device name l3 voltage on the Sdm630.

• Protocol: Modbus RTU
• Data Type: FP32
• Unit: V
• Access: Read Only

How to Read (Python pymodbus)

Use this code snippet to read this specific value via RS485:

from pymodbus.client.sync import ModbusSerialClient

client = ModbusSerialClient(method='rtu', port='/dev/ttyUSB0', baudrate=9600)
client.connect()

# Read device_name L3 Voltage (Address: 4)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=4, count=2, unit=1)

if not result.isError():
    print(f"Raw Value: {result.registers}")
else:
    print("Error reading register")

client.close()

Integration (Home Assistant)

Paste this into your configuration.yaml:

- platform: modbus_controller
  name: "device_name L3 Voltage"
  address: 4
  value_type: FP32
  unit_of_measurement: "V"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Sdm630]

    PLC -- "A+ (D+)" --> Device
    PLC -- "B- (D-)" --> Device
    PLC -- GND --> Device

💡 Engineer's Insight

Analysis: Phase L3 voltage reading. Unit: Volts (V). Indicates electrical potential between L3 and neutral/ground.

Troubleshooting: Zero value may indicate a broken neutral connection, blown fuse, or sensor malfunction. Check wiring and power source.