Stiebel Eltron WPM

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

1. 1Connect the ISG web gateway to the Stiebel Eltron WPM controller following the manufacturer wiring instructions.
2. 2Ensure the ISG web gateway is configured for Modbus TCP and has a static IP address on the local network.
3. 3Connect the ModbusCloud gateway (MCG or MLP series) to the same network as the ISG web gateway.
4. 4In 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.
5. 5Verify that live readings such as outside temperature and fault status appear correctly on the dashboard.
6. 6Check 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

01

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.

02

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.

03

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.

04

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.

Registers (24)

22 read / 7 write

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