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Voltage Phase Modbus Register 30003: Entities name prefix - slave entities prefix name - Voltage Phase L2

Technical documentation for Modbus register 30003 on Voltage Phase. Data type: U DWORD. Includes Python and YAML configuration examples.

January 16, 2026 3 read

Technical Definition

The register entities name prefix - slave entities prefix name - Voltage Phase L2 at address 30003 is used to monitor entities name prefix - slave entities prefix name - voltage phase l2 on the Voltage Phase.

  • Protocol: Modbus RTU
  • Data Type: U DWORD
  • 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 entities_name_prefix - slave_entities_prefix_name - Voltage Phase L2 (Address: 30003)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=30003, 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: "entities_name_prefix - slave_entities_prefix_name - Voltage Phase L2"
  address: 30003
  value_type: U_DWORD
  unit_of_measurement: "V"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Voltage Phase]

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


💡 Engineer's Insight

Analysis: Voltage measurement for Phase 2. Units: Volts (V). Critical for balanced three-phase operation.

Troubleshooting: Zero if phase is unpowered, disconnected, or shorted. Error if readings are unstable or out of range.