
Modbus TCP
SunSpec Model 135 — LFRT
SunSpec
Overview
SunSpec Model 135 (LFRT) is the Low Frequency Ride-Through array model defined by the SunSpec Alliance for grid-connected inverters and distributed energy resources. Used alongside Model 136 (HFRT) and the curve models 141 and 142, it configures how an inverter responds to under-frequency grid events. The template communicates over Modbus TCP and exposes the active curve selector, the module enable flag, windowed activation and revert timers, ramp time, plus the curve-count and scale-factor registers. Pairing this template with the ModbusCloud Gateway lets operators verify and audit frequency protection settings across a fleet of SunSpec-compliant inverters from a single portal.
Use cases
- Verify that the LFRT module-enable flag is active on every inverter after a grid-code change.
- Monitor the active curve index across a multi-inverter site to confirm uniform frequency protection settings.
- Alert on unexpected revert-timer expiry that may indicate a polling interruption or communication loss.




