The gateway connects but all register values read zero.

The most likely cause is a unit ID mismatch: the template defaults to address 1, but the inverter may have been set to a different address. Check the Modbus address on the inverter display or via the Growatt app. Also confirm the baud rate on both sides is 9600 bps with no parity, 1 stop bit.

Values appear intermittently or the gateway reports timeouts.

Growatt RS485 requires a minimum inter-command gap of 850 ms. If your polling interval is shorter, increase it to at least 1 second. Also verify that only one Modbus master is active on the RS485 bus: a Growatt ShineWiFi or smart meter connected to the same SYS COM port can collide with the ModbusCloud Gateway.

The energy and power registers return unexpected large numbers.

The power registers power_a and power_b form a 32-bit uint32 pair split across two consecutive 16-bit input registers. If your integration reads them independently rather than concatenating the two words, you will see incorrect values. Ensure the template is applied as-is without splitting the pair manually.

Is it safe to write to the battery mode registers during normal operation?

Write registers batterymode_a, batterymode_b, and batterymode_c send operational commands directly to the inverter battery management. Writing incorrect values can cause the inverter to enter an unintended charge or discharge mode, potentially triggering protection faults or affecting warranty coverage. Always test write commands during low-load periods and confirm expected behavior before automating.

Free Modbus template: Growatt TL-X(H) Hybrid Inverter (battery)

The Growatt TL-X(H) Hybrid Inverter is a single-phase residential hybrid PV inverter with an integrated battery interface, designed for solar self-consumption and backup power applications. This ModbusCloud template reads the inverter over Modbus RTU via the RS485 SYS COM port, polling AC output power (two 32-bit registers), cumulative energy, and battery state of charge. Three writable battery-mode registers let your portal send charge and discharge control commands to the inverter. Use this template to correlate live generation with storage state and automate battery dispatch from your ModbusCloud dashboard.

Name	Address	Function	Type	Unit	Access
power_a AC output power, first 16-bit word of a 32-bit pair.	3178	FC04	uint32	W	R
power_b AC output power, second 16-bit word of a 32-bit pair.	3180	FC04	uint32	W	R
energy Cumulative AC energy generated, 32-bit unsigned value.	3127	FC04	uint32	Wh	R
soc Battery state of charge, 0 to 100 percent.	3171	FC04	uint16	%	R
batterymode_a Battery mode control setpoint, first configuration word.	3038	FC16	uint16		W
batterymode_b Battery mode control setpoint, second configuration word.	3039	FC16	uint16		W
batterymode_c Battery mode control setpoint, third configuration word.	3049	FC16	uint16		W