Bms Sensors Pace Rs485 Bms Full Modbus Register 18: Cell voltage 4

Technical Definition

The register cell voltage 4 at address 18 is used to monitor cell voltage 4 on the Bms Sensors Pace Rs485 Bms Full.

• Protocol: Modbus RTU
• Data Type: U WORD
• Unit: V
• 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 cell voltage 4 (Address: 18)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=18, 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: "cell voltage 4"
  address: 18
  value_type: U_WORD
  unit_of_measurement: "V"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Bms Sensors Pace Rs485 Bms Full]

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

💡 Engineer's Insight

Analysis: Voltage measurement for cell 4, typically in Volts (V) or milliVolts (mV).

Troubleshooting: Zero or significantly lower than other cells may indicate a faulty cell, poor connection, or a damaged sensor. Could also be a discharged cell.