The gateway connects but registers return zero or no data. Why?

The inverter must be powered by either PV input or AC grid before Modbus TCP responds. If both sources are absent, the communication stack is offline. Confirm the inverter is in an active operating state and that the LAN module LED shows a network link before polling.

Why does the genset_operating_mode register always read zero?

A value of zero typically means the generator input is inactive or not connected. Verify that the generator is wired to the correct GEN input terminal and that the generator feature is enabled in the inverter settings. The register will only change state when the inverter detects a valid generator signal.

Modbus TCP stops responding after a day or two. What is happening?

GoodWe inverters with certain firmware versions can lose local Modbus availability if they lose their cloud connection to the SEMS portal and then restart. Assign a static IP to the inverter, ensure the LAN module firmware is current, and consider allowing periodic SEMS connectivity so firmware-level Modbus enabling is preserved across restarts.

backup_power reads unexpected negative values. Is that a problem?

Register 35169 is typed as int32, so negative values are valid in principle. A negative reading may indicate a measurement polarity mismatch, such as current flowing into rather than out of the backup port. Check that the CT or internal metering is oriented correctly per the inverter installation manual before trusting negative figures.

Free Modbus template: GoodWe Genset

The GoodWe Genset template monitors generator-related operation on GoodWe hybrid energy storage inverters via Modbus TCP. GoodWe hybrid inverters expose a dedicated backup output that can supply critical loads during grid outages, with an optional generator input for extended off-grid runtime. This template reads backup output power (register 35169) and generator operating mode (register 36197), giving installers a direct view of backup load demand and generator state. Connecting through the ModbusCloud Gateway lets you log both values, set threshold alerts, and verify generator handover behavior without on-site visits.

Name	Address	Function	Type	Unit	Access
backup_power Instantaneous AC power delivered to the backup output, in watts.	35169	FC03	int32	W	R
genset_operating_mode Generator operating mode status code, enumerated uint16.	36197	FC03	uint16		R