The gateway connects but soc and power registers return zero or no data.

Modbus TCP access may be disabled by default on the MG100. Confirm the Modbus server is enabled in the Atmozen app or device web interface. Also check that the configured unit ID in ModbusCloud matches the ID assigned on the device. A mismatch returns empty or zero responses without a Modbus exception.

Power readings appear as very large negative numbers. What is wrong?

The power register uses a signed int32 type. If your Modbus client reads it as unsigned, large negative values will appear as numbers above two billion. Confirm your polling tool or the ModbusCloud template is interpreting address 60071 as int32, not uint32. The template input already specifies int32, so no manual override is needed.

Writes to batterymode registers seem to have no effect. How do I diagnose this?

First confirm Modbus write access is enabled on the MG100 separately from read access, as some firmware versions gate writes independently. Use function code 16 as specified. Verify the unit ID is correct and that no firewall or router is blocking write transactions on port 502. Check the MG100 LED status for any fault indication after the write attempt.

Is it safe to write battery mode registers while the system is running?

Use caution with the write registers at addresses 60310, 60311, and 60312. Sending an incorrect mode value can override automatic battery management, force deep discharge, or prevent charging. Always test write commands during low-load periods, confirm the expected mode change in the portal before leaving the site, and review the Atmoce Modbus interface documentation for valid mode values before deploying automated setpoint logic.

Free Modbus template: Atmoce MG100 M-gateway (battery)

The Atmoce MG100 is a microinverter M-Gateway that aggregates data from Atmoce solar and battery systems into a single Modbus TCP interface. This template targets the battery subsystem, reading instantaneous power, cumulative energy, and state of charge at addresses 60071, 60166, and 60095. Three write registers at addresses 60310 to 60312 allow remote battery mode control, covering charge, discharge, and automatic operating states. Connect this template in ModbusCloud to track battery behavior across time and trigger mode changes from your portal without on-site access.

Name	Address	Function	Type	Unit	Access
power Battery instantaneous power, positive for discharge, negative for charge.	60071	FC03	int32	W	R
energy Cumulative battery energy throughput, unsigned 64-bit integer.	60166	FC03	uint64	Wh	R
soc Battery state of charge, 0 to 100 percent.	60095	FC03	uint16	%	R
batterymode_a Battery operating mode setpoint, variant A control word.	60310	FC16	uint16		W
batterymode_c Battery operating mode setpoint, variant C control word.	60312	FC16	uint16		W
batterymode_d Battery operating mode setpoint, variant D control word.	60311	FC16	uint16		W