Itho Ventilation Modbus Register 3011: Highest ppm CO2 non-fan

Technical Definition

The register highest ppm CO2 non-fan at address 3011 is used to monitor highest ppm co2 non-fan on the Itho Ventilation.

• Protocol: Modbus RTU
• Data Type: U WORD
• Unit: ppm
• 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 highest ppm CO2 non-fan (Address: 3011)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=3011, 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: "highest ppm CO2 non-fan"
  address: 3011
  value_type: U_WORD
  unit_of_measurement: "ppm"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Itho Ventilation]

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

💡 Engineer's Insight

Analysis: Highest detected CO2 concentration (ppm) when fan is inactive.

Troubleshooting: Zero suggests CO2 sensor malfunction or extremely low ambient CO2 levels.