ModBus Battery SOC

soc.py

#!/usr/bin/env python3

from pymodbus.constants import Defaults
from pymodbus.constants import Endian
from pymodbus.client.sync import ModbusTcpClient as ModbusClient
from pymodbus.payload import BinaryPayloadDecoder

BmvID = 223

ip = "localhost" # ip address of GX device or if on venus local try localhost

# Local network ip address of Cerbo GX. Default port 502
client = ModbusClient(ip, port='502')

# All modbus variable requests are sent to this function and it return's the requested value
def modbus_register(address, unit):
    msg     = client.read_holding_registers(address, unit=unit)
    decoder = BinaryPayloadDecoder.fromRegisters(msg.registers, byteorder=Endian.Big)
    msg     = decoder.decode_16bit_int()
    return msg

BatterySOC  = modbus_register(266, BmvID) / 10

print(f"BatterySOC {BatterySOC}")