Why do I see NaN instead of a value for register 31249?

The SMA Modbus interface returns NaN when a register has no valid data. For the active power register at 31249, this typically means the Modbus server is not enabled, or the unit ID in the ModbusCloud portal does not match the one configured on the device. Confirm the Modbus interface is active and the unit IDs match, then retry.

Why do the current registers show implausible values or all zeros?

Registers 31535, 31537, and 31539 use a FIX3 scaling format, meaning the raw int32 value must be divided by 1000 to get amperes. If your client is not applying this scaling, readings will appear as very large integers. Check that the ModbusCloud template is applying the correct scale factor before displaying values.

The gateway connects but no register values appear. What should I check?

The SMA Data Manager (grid) requires a static IP address. If the device obtains a new IP via DHCP after a restart, the address configured in the ModbusCloud portal becomes stale. Assign a static IP or a static DHCP lease to the device, update the portal accordingly, and restart the Gateway poll.

I receive Modbus error code 11 on every request. What causes this?

Error code 11 is returned when the unit ID in the Modbus request does not match the unit ID set on the device. Log into the SMA Data Manager (grid) web interface to find the configured unit ID, then update the ModbusCloud portal device settings to match that value exactly.

Free Modbus template: SMA Data Manager (grid)

The SMA Data Manager (grid) is a PV system energy management controller that acts as the central Modbus TCP gateway between a solar installation and external monitoring systems or grid operators. This template reads the four core grid-connection registers: total active power at the point of common coupling (PCC) and per-phase AC currents on lines L1, L2, and L3. Connecting the SMA Data Manager (grid) to ModbusCloud gives installers and asset managers a continuous, cloud-hosted view of grid exchange and phase-load balance without requiring a separate energy meter.

Name	Address	Function	Type	Unit	Access
power Active power of the system at the point of common coupling, in watts.	31249	FC03	int32	W	R
currents_a AC phase current on line conductor L1 at the PCC.	31535	FC03	int32	A	R
currents_b AC phase current on line conductor L2 at the PCC.	31537	FC03	int32	A	R
currents_c AC phase current on line conductor L3 at the PCC.	31539	FC03	int32	A	R