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.

Free Modbus template: 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.

Name	Address	Function	Type	Unit	Access
getmode Current SG Ready operating mode, read from the heat pump manager.	5167	FC03	uint16		R
setmode SG Ready operating mode setpoint, written to the heat pump manager.	5167	FC16	uint16		W
power Current heat pump power consumption or output level.	5170	FC04	uint16	W	R
setmaxpower Maximum power limit setpoint for the heat pump.	5182	FC16	int16	W	W
temp Measured temperature, typically outside or flow temperature.	3	FC04	int16	°C	R
limittemp Configured temperature limit for the current operating mode.	5048	FC04	int16	°C	R