Jsy Mk 354 Modbus Register 318: Reverse Active Energy L2

Technical Definition

The register Reverse Active Energy L2 at address 318 is used to monitor reverse active energy l2 on the Jsy Mk 354.

• Protocol: Modbus RTU
• Data Type: U DWORD
• Unit: kWh
• 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 Reverse Active Energy L2 (Address: 318)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=318, 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: "Reverse Active Energy L2"
  address: 318
  value_type: U_DWORD
  unit_of_measurement: "kWh"

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 reverse active energy (kWh) generated by Phase L2. Indicates power flowing back from the load to the source.

Troubleshooting: Zero if no generation on L2. Check for backfeed sources or incorrect CT/VT polarity on Phase L2.