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Bms Combine Modbus Client Modbus Register 28: YamBMS Errors Bitmask

Technical documentation for Modbus register 28 on Bms Combine Modbus Client. Data type: U WORD. Includes Python and YAML configuration examples.

January 16, 2026 3 read

Technical Definition

The register YamBMS Errors Bitmask at address 28 is used to monitor yambms errors bitmask on the Bms Combine Modbus Client.

  • Protocol: Modbus RTU
  • Data Type: U WORD
  • Unit:
  • 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 YamBMS Errors Bitmask (Address: 28)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=28, 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: "YamBMS Errors Bitmask"
  address: 28
  value_type: U_WORD
  unit_of_measurement: ""

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Bms Combine Modbus Client]

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


💡 Engineer's Insight

Analysis: Bitmask indicating various error conditions within the YamBMS system. Each bit corresponds to a specific fault.

Troubleshooting: A value of 0 means no errors are currently reported. Any non-zero value requires checking individual bits for specific fault identification.