Glen Dimplex WPM (SG Ready)
The Glen Dimplex WPM (Heat Pump Manager) is a controller for Glen Dimplex heat pumps that supports SG Ready grid integration, enabling smart energy management in residential and light-commercial heating systems. This Modbus TCP template reads the current SG Ready operating mode and measured temperature, while providing write access to the operating mode setpoint, maximum power limit, and temperature limit. Together these registers let you coordinate heat pump operation with surplus PV energy or grid signals in real time. Connecting via the NWPM Ethernet extension gives your ModbusCloud Gateway direct TCP access to the WPM.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 6, read and write
- Brand
- Glen Dimplex
- Last updated
Registers (6)
4 read, 2 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| getmode | Read | ||||
| setmode | Write | ||||
| power | W | Read | |||
| setmaxpower | W | Write | |||
| temp | °C | Read | |||
| limittemp | °C | Read |
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Use cases
- Monitor the current SG Ready operating mode to confirm the heat pump responds to PV surplus signals correctly.
- Track measured temperature against the configured temperature limit to verify heating setpoint compliance over time.
- Alert on unexpected operating mode changes that may indicate a failed SG Ready command or communication dropout.
- Report power consumption readings to correlate heat pump load with solar generation curves during the day.
- Verify maximum power limit setpoint after each grid signal event to confirm the WPM received and retained the value.
Installation
Enable Modbus TCP on the NWPM Ethernet extension by logging into the pcoWEB interface, navigating to preferences, then network and firmware, and activating the Modbus TCP option.
Connect the NWPM extension to the same local network as the ModbusCloud Gateway using a Cat 5e or higher S/FTP cable, and note the IP address assigned by your router.
In the ModbusCloud portal, add a new device, import the Glen Dimplex WPM (SG Ready) template, enter the NWPM IP address, set the Modbus unit ID to 1, and save.
Spot-check the connection by reading the getmode register (address 5167) in the portal live view and confirm the value matches the operating mode shown on the WPM display.
Things to watch for
Why does the gateway connect but all register values show zero or error?
Confirm that Modbus TCP is explicitly enabled in the pcoWEB interface of the NWPM extension. The module ships with Modbus TCP disabled by default. Also verify the IP address is reachable from the Gateway's network segment and that no firewall blocks port 502.
The getmode and power registers return no data. What is wrong?
Register 5167 and 5170 use different function codes: FC 3 (holding registers) and FC 4 (input registers) respectively. Ensure your portal template is not overriding the function codes. Using FC 4 for address 5167 will always fail. The template already assigns the correct codes per register.
I wrote a new mode to setmode but the heat pump did not change. Why?
The WPM firmware requires the write transaction to complete with a confirmation step. Some implementations report that writing a value together with a boolean TRUE flag is rejected. Write the mode value first without the confirmation bit set, and allow the WPM to acknowledge the change before verifying with a subsequent read of getmode.
Is it safe to write setmode and setmaxpower during normal operation?
Use caution. Writing incorrect operating mode values or excessively low power limits via setmode (address 5167) and setmaxpower (address 5182) can push the heat pump outside intended operating parameters, potentially triggering protection shutdowns or affecting the manufacturer warranty. Always test write commands in a controlled state and verify the result immediately by reading back getmode.
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