Config Modbus Register 2: Conductivity 1 dS/m = 1 mS/cm

Technical Definition

The register Conductivity 1 dS/m = 1 mS/cm at address 2 is used to monitor conductivity 1 ds/m = 1 ms/cm on the Config.

• Protocol: Modbus RTU
• Data Type: U WORD
• Unit: ms/cm
• 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 Conductivity 1 dS/m = 1 mS/cm (Address: 2)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=2, 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: "Conductivity 1 dS/m = 1 mS/cm"
  address: 2
  value_type: U_WORD
  unit_of_measurement: "ms/cm"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

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

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

💡 Engineer's Insight

Analysis: Electrical conductivity measurement in deciSiemens per meter (dS/m) or milliSiemens per centimeter (mS/cm). Indicates water purity or ion concentration.

Troubleshooting: Zero reading may indicate sensor malfunction, complete deionization, or incorrect wiring. Check sensor integrity and calibration.