Baxi esp Modbus Register 404: HM002 T. Retorno Bomba

Technical Definition

The register HM002 T. Retorno Bomba at address 404 is used to monitor hm002 t. retorno bomba on the baxi esp.

• Protocol: Modbus RTU
• Data Type: S WORD
• Unit: °C
• 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 HM002 T. Retorno Bomba (Address: 404)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=404, 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: "HM002 T. Retorno Bomba"
  address: 404
  value_type: S_WORD
  unit_of_measurement: "°C"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

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

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

💡 Engineer's Insight

Analysis: HM002 Pump Return Temperature. Likely in Celsius (°C). Indicates the Temperature of the fluid returning from the pump circuit.

Troubleshooting: Zero value suggests pump inactivity, line blockage, or sensor issue. Error points to potential sensor or communication problems.