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Jsy Mk 354 Modbus Register 292: Reactive Energy L2

Technical documentation for Modbus register 292 on Jsy Mk 354. Data type: U DWORD. Includes Python and YAML configuration examples.

January 16, 2026 1 min read

Technical Definition

The register Reactive Energy L2 at address 292 is used to monitor reactive energy l2 on the Jsy Mk 354.

  • Protocol: Modbus RTU
  • Data Type: U DWORD
  • Unit: kVARh
  • 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 Reactive Energy L2 (Address: 292)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=292, 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: "Reactive Energy L2"
  address: 292
  value_type: U_DWORD
  unit_of_measurement: "kVARh"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Jsy Mk 354]

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


💡 Engineer's Insight

Analysis: Measures reactive energy (VARh) consumed or produced by phase L2. Essential for balanced three-phase system analysis.

Troubleshooting: Zero value may signal issues with L2 load or meter reading. Verify phase voltage and current readings for L2.