Iem3155-8266 Modbus Register 3109: Frequency

Technical Definition

The register Frequency at address 3109 is used to monitor frequency on the iem3155-8266.

• Protocol: Modbus RTU
• Data Type: FP32
• Unit: Hz
• 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 Frequency (Address: 3109)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=3109, 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: "Frequency"
  address: 3109
  value_type: FP32
  unit_of_measurement: "Hz"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[iem3155-8266]

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

💡 Engineer's Insight

Analysis: Electrical frequency of the supply, typically in Hertz (Hz). Standard grid frequency.

Troubleshooting: Zero or incorrect frequency signifies a severe power grid issue or meter failure. Contact utility provider.