Heatpump Modbus Register 8: Entity prefix Forced Tank Backup Heater

Technical Definition

The register entity prefix Forced Tank Backup Heater at address 8 is used to monitor entity prefix forced tank backup heater on the heatpump.

• Protocol: Modbus RTU
• Data Type: U WORD
• Unit:
• 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 entity_prefix Forced Tank Backup Heater (Address: 8)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=8, 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: "entity_prefix Forced Tank Backup Heater"
  address: 8
  value_type: U_WORD
  unit_of_measurement: ""

Connection Diagram

Here is the standard RS485 wiring for this configuration:

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

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

💡 Engineer's Insight

Analysis: Status of forced tank backup heater. '1' for active, '0' for inactive.

Troubleshooting: Control signal error, thermostat setpoint not met, or backup heater element failure.