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Ctc Ecozenith I250 Modbus Register 648: Heat pump 1: Charge pump value (%)

Technical documentation for Modbus register 648 on Ctc Ecozenith I250. Data type: S WORD. Includes Python and YAML configuration examples.

January 16, 2026 3 read

Technical Definition

The register Heat pump 1: Charge pump value (%) at address 648 is used to monitor heat pump 1: charge pump value (%) on the Ctc Ecozenith I250.

  • Protocol: Modbus RTU
  • Data Type: S 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 Heat pump 1: Charge pump value (%) (Address: 648)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=648, 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: Charge pump value (%)"
  address: 648
  value_type: S_WORD
  unit_of_measurement: "%"

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: Charge pump value (%) indicates the operational status or speed of the charge pump. Units: Percentage (0-100%). Relevant for systems requiring precise refrigerant charging.

Troubleshooting: Zero value implies the pump is off or not functioning. Deviations from expected values could indicate control issues or pump malfunction.