Ctc Ecozenith I250 Modbus Register 641: Heat pump 1: Superheat

Technical Definition

The register Heat pump 1: Superheat at address 641 is used to monitor heat pump 1: superheat on the Ctc Ecozenith I250.

• 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 Heat pump 1: Superheat (Address: 641)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=641, 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: "Heat pump 1: Superheat"
  address: 641
  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[Ctc Ecozenith I250]

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

💡 Engineer's Insight

Analysis: Superheat indicates the Temperature difference between the refrigerant vapor Temperature and its saturation Temperature at the measurement point. Units: °C or °F. Crucial for system efficiency and protection.

Troubleshooting: Low or zero superheat may indicate liquid floodback, damaging the compressor. High superheat suggests insufficient refrigerant or a restricted expansion device.