Default Aio 422 R1 Plc Modbus Register 391: Aio prefix PID2 PV Raw

Technical Definition

The register aio prefix PID2 PV Raw at address 391 is used to monitor aio prefix pid2 pv raw on the Default Aio 422 R1 Plc.

• Protocol: Modbus RTU
• Data Type: S 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 aio_prefix PID2 PV Raw (Address: 391)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=391, 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: "aio_prefix PID2 PV Raw"
  address: 391
  value_type: S_WORD
  unit_of_measurement: ""

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[Default Aio 422 R1 Plc]

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

💡 Engineer's Insight

Analysis: Raw Process Variable input for PID controller 2. Corresponds to the measured process value.

Troubleshooting: Zero PV may indicate a sensor failure, wiring issue, or the actual process value being zero. Verify sensor readings and process conditions.