Pack Modbus Register 29: Friendly name pack Cell Voltage 15

Technical Definition

The register friendly name pack Cell Voltage 15 at address 29 is used to monitor friendly name pack cell voltage 15 on the Pack.

• 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 friendly_name pack Cell Voltage 15 (Address: 29)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=29, 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 pack Cell Voltage 15"
  address: 29
  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[Pack]

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

💡 Engineer's Insight

Analysis: Voltage of Cell 15 within the battery pack, typically measured in Volts (V). Crucial for identifying cells deviating from the norm.

Troubleshooting: Look for: internal cell shorts, faulty connections, sensor malfunction, or BMS read errors.