Why does the gateway return error code 11 on every poll?

Error code 11 means the Modbus unit ID in your portal does not match the unit ID configured on the inverter. Open the inverter web interface, note the unit ID under the Modbus or External Communication section, and update the unit ID field in your ModbusCloud template assignment to match exactly.

The cur_bat_cha and cur_bat_dsch registers both read NaN. Why?

SMA documentation notes these registers return NaN when no battery inverter is detected in the system. Confirm the battery is powered, the BMS communication cable is connected to the inverter, and the inverter has completed its initialisation sequence before polling those addresses.

64-bit counters at addresses 31397 and 31401 look corrupt. What is wrong?

64-bit SMA registers must be read as a single contiguous 64-bit operation. Reading them as two separate 32-bit requests can produce inconsistent half-values. Ensure the ModbusCloud Gateway reads the full four-register block in one function-code 3 request, which the template is configured to do by default.

Is it safe to write to set_active_power and set_control_mode in normal operation?

Exercise caution. Writing an active-power setpoint via register 40149 without first enabling external control through set_control_mode (40151) may be ignored or cause unexpected behaviour. Never write these registers cyclically in a tight loop; SMA documentation warns that cyclical writes to non-control parameters can damage flash memory. Test with small setpoint increments and confirm the inverter responds as expected before deploying automated control.

Free Modbus template: SMA StpSe Battery

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Free Modbus template: SMA StpSe Battery | ModbusCloud

Registers (16)

13 read / 3 write

Name	Address	Function	Type	Unit	Access
current Battery DC current, signed, positive during charge.	•••	•••	•••	A	R
soc Battery state of charge, 0 to 100 percent.	•••	•••	•••	%	R
voltage Battery DC voltage in volts.	•••	•••	•••	V	R
bat_status Battery operating status, encoded enumeration value.	•••	•••	•••		R
cur_bat_cha Instantaneous battery charge power in watts.	•••	•••	•••	W	R
cur_bat_dsch Instantaneous battery discharge power in watts.	•••	•••	•••	W	R
bat_chrg Cumulative battery charge energy counter in watt-hours.	•••	•••	•••	Wh	R
bat_dsch Cumulative battery discharge energy counter in watt-hours.	•••	•••	•••	Wh	R
charge_max_current Maximum allowable battery charge current in amperes.	•••	•••	•••	A	R
discharge_max_current Maximum allowable battery discharge current in amperes.	•••	•••	•••	A	R
act_bat_chrg Actual accumulated charge energy since installation, watt-hours.	•••	•••	•••	Wh	R
act_bat_dsch Actual accumulated discharge energy since installation, watt-hours.	•••	•••	•••	Wh	R
capacity Configured battery capacity in watt-hours.	•••	•••	•••	Wh	R
set_active_power Active power setpoint; positive to discharge, negative to charge.	•••	•••	•••	W	W
set_control_mode Battery control mode selector; enables or disables external power control.	•••	•••	•••		W
set_reactive_power Reactive power setpoint in volt-amperes reactive.	•••	•••	•••	W	W

Loading registers…

SMA StpSe Battery

Overview

Use cases

Installation

Things to watch for

Registers (16)

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