Heatpump Modbus Register 111: System Total Water Outlet Temperature T1B

Technical Definition

The register System Total Water Outlet Temperature T1B at address 111 is used to monitor system total water outlet Temperature t1b on the heatpump.

• Protocol: Modbus RTU
• Data Type: S WORD
• Unit: °C
• 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 System Total Water Outlet Temperature T1B (Address: 111)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=111, 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: "System Total Water Outlet Temperature T1B"
  address: 111
  value_type: S_WORD
  unit_of_measurement: "°C"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[heatpump]

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

💡 Engineer's Insight

Analysis: System total water outlet Temperature (T1B). Units: °C. Secondary outlet Temperature.

Troubleshooting: Zero value suggests sensor error, pump issue, or no flow in this part of the system.