Stiebel Eltron WPM
Monitors and controls Stiebel Eltron WPM heat pumps via Modbus TCP
This template reads and controls Stiebel Eltron WPM heat pumps via Modbus TCP through an ISG web gateway. It provides live temperature readings, fault monitoring, and allows adjustment of operating modes and temperature setpoints for heating circuits and domestic hot water.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 24, read and write
- Brand
- Stiebel Eltron
- Key readings
- Outside temperature · Flow and return temperatures · Buffer temperature (actual/set) · DHW actual/set temperature · HK1/HK2 actual/set temperatures · Fault status and message number
- Available commands
- Operating mode · HK1/HK2 comfort and eco temperatures · DHW comfort/eco temperature
- Compatible models
- Stiebel Eltron WPM
- Last updated
Registers (24)
22 read, 7 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| 519 - Set buffer temperature | °C | Read | |||
| 518 - Actual buffer temperature | °C | Read | |||
| 513 - Actual flow temperature WP | °C | Read | |||
| 508 - Actual temperature HK 1 | °C | Read | |||
| 516 - Actual return temperature | °C | Read | |||
| 510 - Set temperature HK 1 | °C | Read | |||
| 2504 - Fault ststus | Read | ||||
| 1501 - Operating mode | Read and write | ||||
| 1504 - HK 1 heating curve rise | Read | ||||
| 2508 - Message number | Read | ||||
| 522 - DHW actual temperature | °C | Read | |||
| 523 - DHW set temperature | °C | Read | |||
| 507 - Outside temperature | °C | Read | |||
| 501 - Actual temperature FE7 | °C | Read | |||
| 502 - Set temperature FE7 | °C | Read | |||
| 511 - Actual temperature HK2 | °C | Read | |||
| 512 - Set temperature HK 2 | °C | Read | |||
| 1502 - HK 1 comfort temperature | °C | Read and write | |||
| 1505 - HK 2 comfort temperature | °C | Read and write | |||
| 1503 - HK 1 eco temperature | °C | Read and write | |||
| 1506 - HK 2 eco temperature | °C | Read and write | |||
| 1507 - HK 2 heating curve rise | Read | ||||
| 1511 - DHW eco temperature | °C | Write | |||
| 1510 - DHW comfort temperature | °C | Write |
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Use cases
- Monitor outside, flow, return, and buffer temperatures of the WPM heat pump on a live cloud dashboard.
- Create an alert when a fault status is detected on the heat pump to reduce response time.
- Adjust HK1 and HK2 comfort and eco temperature setpoints remotely without a site visit.
- Log DHW actual and set temperatures over time to verify the system meets hot water demand.
- Switch the heat pump operating mode remotely for seasonal commissioning or maintenance purposes.
- Compare buffer tank setpoint versus actual temperature to identify underperformance early.
Installation
Connect the ISG web gateway to the Stiebel Eltron WPM controller following the manufacturer wiring instructions.
Ensure the ISG web gateway is configured for Modbus TCP and has a static IP address on the local network.
Connect the ModbusCloud Gateway to the same network as the ISG web gateway.
In the ModbusCloud platform, import the Stiebel Eltron WPM template and enter the IP address and Modbus TCP port (default 502) of the ISG web gateway.
Verify that live readings such as outside temperature and fault status appear correctly on the dashboard.
Check that control registers respond by changing the operating mode or a temperature setpoint and confirming the update on the WPM display.
Things to watch for
Why do my temperature readings appear incorrect or extremely high?
Some registers use int16 (signed) format while others use uint16 (unsigned). If a negative temperature is read as uint16, it will display as a very large number. Verify the data type setting for each register in the template configuration.
Why can I not connect to the ISG web gateway via Modbus TCP?
Confirm that Modbus TCP is enabled in the ISG web gateway settings and that the gateway has a static IP address. Check that the ModbusCloud gateway is on the same subnet and that no firewall is blocking port 502.
The register numbers in the template do not match the ISG documentation. What is wrong?
The template uses 1-based register numbering, but actual Modbus addresses are 0-based. Register 519 in the template maps to address 518 on the wire. Most Modbus TCP clients handle this offset automatically, but verify your gateway settings if readings are shifted.
Can I control multiple heating circuits independently?
Yes. The template exposes separate comfort and eco setpoint registers for HK1 and HK2. You can adjust each heating circuit independently through the ModbusCloud dashboard or automation rules.
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