The gateway connects but all register values read zero or timeout. What is wrong?

Modbus TCP must be explicitly enabled in the heat pump display under the network or communication settings menu. Also confirm the heat pump firmware is version 2.2.1 or later for basic Modbus TCP support. Without activation, the heat pump will not respond to any Modbus queries even if the TCP connection appears open.

Register 1911 shows a code like 10 or 20. How do I read the SG Ready state?

Register 1911 returns an enumerated value, not a boolean. The values are: 10 = normal, 20 = blocked, 30 = cheap energy, 40 = free energy (boost). Map these in your portal dashboard accordingly. A raw value of 0 usually indicates Modbus TCP is active but SG Ready via API has not been enabled in the unit settings.

Writing to register 6008 has no effect on heat pump behavior. Why?

SG Ready control via Modbus TCP requires firmware version 4.7.5 or later on NIBE S-Series units. Additionally, SG Ready via API must be enabled within the heat pump menu before register 6008 writes take effect. Without that prerequisite, writes will be acknowledged by Modbus but silently ignored by the controller.

Can I freely write any value to register 6008 without risk to the installation?

Use caution when writing to register 6008. Setting mode 0 (blocking) prevents the compressor from running and can affect comfort or hot water availability during peak demand. Setting mode 3 (boost) forces maximum heat output and may run the unit at conditions outside its normal control envelope. Always test setpoint changes in a controlled window and confirm via getmode (register 1911) that the unit accepted the command.

Free Modbus template: NIBE Nibe S-Series (SG Ready)

The NIBE Nibe S-Series (SG Ready) is a ground source and air-to-water heat pump range designed for residential and light-commercial heating and domestic hot water. This ModbusCloud template connects over Modbus TCP and reads the active SG Ready operating state, hot water temperature, instantaneous power consumption, and accumulated energy. It also writes the SG Ready mode setpoint, enabling four operating levels from load blocking to full boost. Installers and energy managers gain direct visibility and demand-response control of NIBE S-Series heat pump operation from a single portal.

Name	Address	Function	Type	Unit	Access
setmode SG Ready mode setpoint: 0 blocking, 1 normal, 2 cheap energy, 3 boost.	6008	FC16	int16		W
getmode Active SG Ready state: 10 normal, 20 blocked, 30 cheap, 40 boost.	1911	FC04	uint16		R
temp Hot water temperature, scaled by 0.1, unit degrees Celsius.	9	FC04	uint16	°C	R
power Current electrical power consumption of the heat pump, in watts.	2305	FC04	uint16	W	R
energy Accumulated energy reading from the heat pump system.	3823	FC04	uint16		R