D1 Mini Pro Modbus Modbus Register 16: Friendly name LastValidU1

Technical Definition

The register friendly name LastValidU1 at address 16 is used to monitor friendly name lastvalidu1 on the D1 Mini Pro Modbus.

• 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 LastValidU1 (Address: 16)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=16, 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 LastValidU1"
  address: 16
  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[D1 Mini Pro Modbus]

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

💡 Engineer's Insight

Analysis: Indicates the last successfully read value of a primary input or sensor 'U1'. Units depend on the sensor (e.g., Volts, Amps, Degrees).

Troubleshooting: Could be 0 if the sensor is offline, faulty, or if communication with the device is lost. Check sensor connection and device status.