
Modbus TCP
SunSpec Model 709 — DER Trip LF
SunSpec
Overview
SunSpec Model 709 (DER Trip LF) is the IEEE 1547-2018 low-frequency trip information model for distributed energy resources such as inverters and battery storage systems. Via Modbus TCP, this template reads and manages the fixed-block header registers covering model identity, length, enable state, curve-adoption request and result, curve geometry metadata, and the Hz and Tms scale factors that govern how frequency-time trip curves are interpreted. Knowing whether the trip function is active and which curve set is armed lets commissioning engineers verify grid-protection compliance without opening the device web interface.
Use cases
- Verify the low-frequency trip function is enabled on all site inverters after initial commissioning.
- Monitor the adopt-curve result register to confirm a new trip curve was accepted without errors.
- Track the active curve-set index to detect unauthorised changes to low-frequency protection settings.
- Alert on unexpected disable of the trip function, which may indicate a misconfiguration or firmware issue.




