Heatpump Modbus Register 253: Comfort Parameter Reserved 3

Technical Definition

The register Comfort Parameter Reserved 3 at address 253 is used to monitor comfort parameter reserved 3 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 Comfort Parameter Reserved 3 (Address: 253)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=253, 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: "Comfort Parameter Reserved 3"
  address: 253
  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: Reserved register for comfort-related parameters. Its specific function is undefined and likely for future use or proprietary settings within the comfort control system.

Troubleshooting: As a reserved register, a value of '0' is expected unless actively programmed. Any unexpected non-zero value could indicate a firmware glitch or unintended write.