
Modbus TCP
SunSpec Model 123 — Immediate Controls
SunSpec
Overview
SunSpec Model 123 is a standardized inverter control model defined by the SunSpec Alliance for grid-connected distributed energy resources. This Modbus TCP template targets the Immediate Controls block used by SMA, Fronius, Kostal, and other SunSpec-certified inverters. It exposes grid connection control (conn), active power limiting (wmaxlimpct and wmaxlim_ena), fixed power factor (outpfset and outpfset_ena), and reactive power setpoints (varwmaxpct, varmaxpct, varavalpct, varpct_ena) together with their time-window, reversion, and ramp registers. Importing this template into ModbusCloud gives installers a ready-made interface to read and write Model 123 controls across any compliant device without manual register mapping.
Use cases
- Monitor active power limit setpoint (wmaxlimpct) to verify curtailment commands are applied as dispatched by a DSO or EMS.
- Track power factor setpoint (outpfset) over time to confirm reactive power compliance with local grid code requirements.
- Alert when the grid connection register (conn) changes unexpectedly, indicating an unplanned inverter disconnect event.




