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Esp%20Inverter Modbus Register 166: Friendly name Aux Output Power

Technical documentation for Modbus register 166 on Esp%20Inverter. Data type: S WORD. Includes Python and YAML configuration examples.

January 16, 2026 3 read

Technical Definition

The register friendly name Aux Output Power at address 166 is used to monitor friendly name aux output power on the Esp%20Inverter.

  • Protocol: Modbus RTU
  • Data Type: S WORD
  • Unit: W
  • 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 friendly_name Aux Output Power (Address: 166)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=166, 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: "friendly_name Aux Output Power"
  address: 166
  value_type: S_WORD
  unit_of_measurement: "W"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Esp%20Inverter]

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


💡 Engineer's Insight

Analysis: Aux Output Power: Power consumed/supplied by auxiliary output. Units Watts (W).

Troubleshooting: Zero could mean no auxiliary load, device failure, or output disabled. Verify auxiliary device and inverter setting.