The gateway connects but both registers return NaN. What is wrong?

NaN is the SMA-defined response for a register that is defined in the profile but whose value cannot be determined at query time. Confirm that the Modbus server is active in the Data Manager web interface under the communication settings. After any factory reset, the Modbus interface defaults to disabled and must be re-enabled manually.

Register 30775 reads zero even though inverters are producing power.

Address 30775 reports the aggregated PV active power accumulated from all connected inverters. If inverters have not been fully commissioned in the Data Manager, their values will not appear in the aggregate. Check that all inverters are visible and online in the Data Manager device list before polling this register.

Values are being read but the numbers look byte-swapped or scaled incorrectly.

The SMA Data Manager stores multi-register values in Motorola Big Endian format: the high byte is transmitted first. Ensure your Modbus client is configured for Big Endian word order. Register 30775 is a signed 32-bit integer and register 30513 is an unsigned 64-bit integer spanning four consecutive 16-bit registers; reading fewer registers than the full data block will produce corrupt values.

The Data Manager loses connection intermittently after a few hours.

Dynamic DHCP can reassign the Data Manager's IP address when the lease expires, breaking the Modbus TCP connection. Assign a static IP address on the device itself or configure a static DHCP reservation in your router using the device MAC address. Reconnection will then be stable across lease renewals.

Free Modbus template: SMA Data Manager (pv)

The SMA Data Manager (pv) is a system-level energy management gateway that aggregates PV generation data from multiple SMA inverters into a single Modbus TCP interface. This template reads two key system registers: current active power output across all line conductors (address 30775) and total cumulative feed-in energy (address 30513). Both values are 30000-series read-only registers served over Modbus TCP on port 502. Connecting via the ModbusCloud Gateway gives installers and asset managers a continuous, cloud-accessible view of site-level PV production without polling individual inverters.

Name	Address	Function	Type	Unit	Access
power Current PV feed-in active power across all line conductors, in watts.	30775	FC03	int32	W	R
energy Total cumulative energy fed in across all line conductors, in watt-hours.	30513	FC03	uint64	Wh	R