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SRNE ASP48120SH3 Modbus Register Map (validated)

Validated Modbus register map for the SRNE ASP48120SH3 three-phase hybrid inverter, verified register-by-register against the live Nansana unit, including a grid-off / grid-on transition test on 2026-07-27 that resolved the previously-unknown registers and corrected the battery-current sign.

Bus: RS485, 9600 8N1, function code 03 (read holding registers), slave address 1. Source of truth (code): src/inverter/registers.py in nfe-modbus-energy-logger.

Valid register ranges (probed live)

  • P00 product info: 0x0000 to 0x0049
  • P01 battery / DC: 0x0100 to 0x0111
  • P02 inverter telemetry: 0x0200 to 0x023F (0x0240 and beyond return "Illegal data address")
  • P03 control commands: 0xDF00 to 0xDF09 (write-only, read back 0)
  • Settings E (writable params): 0xE001 to 0xE02D ; Settings F: 0xF000 to 0xF01F

Live telemetry, full per-phase - VERIFIED

quantity phase A phase B phase C notes
grid voltage 0x0213 0x022A 0x022B x0.1 V (all go to 0 when grid is off)
grid current 0x0214 0x0238 0x0239 x0.1 A. B/C live in the extended block, CONFIRMED grid-side by the transition test
grid frequency 0x0215 - - x0.01 Hz
grid active power 0x023A 0x023B 0x023C W (extended block, grid-side)
inverter voltage 0x0216 0x022C 0x022D x0.1 V
inverter current 0x0217 0x022E 0x022F x0.1 A (rises when off-grid, inverter sources the load)
inverter frequency 0x0218 - - x0.01 Hz
load current 0x0219 0x0230 0x0231 x0.1 A (load-side, holds through the transition)
load active power 0x021B 0x0232 0x0233 W. No total register: sum the three phases
load reactive power (derive) 0x0234 0x0235 var. Phase A: S=sqrt(P^2+Q^2) not given, derive
load apparent power 0x021C (derive) (derive) VA. B/C: derive S = sqrt(P^2 + Q^2)
load ratio 0x021F 0x0236 0x0237 %

Other P02: state 0x0210, password status 0x0211, bus V 0x0212 (x0.1) = PBus 0x0228 + NBus 0x0229, inverter DC component 0x021D (mV), mains charge current 0x021E (x0.1 A), heat-sink temps 0x0220/0x0221/0x0222 (x0.1 C, 0x0223 bogus), PV charge current 0x0224 (0, no PV), inverter fault 0x0226, charge status 0x0227. Extended grid block tail 0x023D/0x023E/0x023F (0/221/245/309 on grid) is grid-side reactive/apparent, exact split still to confirm.

Battery / DC (P01) - VERIFIED

SOC 0x0100 (%), battery V 0x0101 (x0.1 V), battery current 0x0102 (x0.1 A, signed), device temp 0x0103 (reads 0, dead), DC load 0x0104-0x0106 (0), PV1 0x0107-0x0109 (0, no PV), charge state 0x010B, charge power 0x010E, PV2 0x010F-0x0111 (0).

IMPORTANT - battery current sign is POSITIVE = DISCHARGE on this unit (the OPPOSITE of the generic SRNE V1.7 doc). Proven by the 2026-07-27 off-grid test: with grid and PV both at 0, the battery is the only source, and while it was unambiguously discharging ~750 W to the loads it read +14.2 A; when the grid returned, discharge collapsed to +0.4 A (idle). So positive current = discharge, negative = charge.

Grid-off / grid-on transition test (2026-07-27) - what died vs held

  • GRID-side (went to 0 when utility cut, back live when restored): grid V A/B/C (0x0213/0x022A/0x022B), grid I A (0x0214), grid freq (0x0215), and the whole extended block 0x0238 to 0x023F (grid I B/C + grid power). This is how the extended block was identified.
  • LOAD-side (held through the transition, source-independent): load I/P/Q per phase (0x0219, 0x021B, 0x0230-0x0237).
  • INVERTER-side (rose off-grid as it took the load): inverter I A/B/C (0x0217/0x022E/0x022F).
  • STATE 0x0210: 2 = on-grid / mains-bypass, 3 = off-grid / inverter-powered (both codes validated by the transition). Charge state 0x010B: 0 off-grid, 1 on-grid.

Corrections vs the generic SRNE V1.7 doc (do NOT trust the generic enums/signs)

  • Battery current sign: positive = discharge (doc says positive = charge - WRONG here).
  • Machine state 0x0210: 2 = running/mains-bypass, 3 = off-grid. NOT the generic "initialization/soft-start".
  • Power factor 0x021A reads 0. Derive PF = active (0x021B) / apparent (0x021C).
  • Device temperature 0x0103 reads 0. Use heat-sink temps 0x0220 to 0x0222.

For the OpenEMS driver (important)

  • There is NO inverter-output-power and NO ESS/battery AC-power register. The ESS SymmetricEss.ACTIVE_POWER must be DERIVED from battery DC power (0x0101 x 0x0102). Do NOT map load power 0x021B (that is the loads, phase A only).
  • Dc/ESS power sign: since positive battery current = discharge, DcDischargePower = +V x I (do NOT negate). A negated formula reports a real discharge as a charge.
  • Grid meter can now have per-phase current and power: grid I A/B/C (0x0214/0x0238/0x0239) and grid active power A/B/C (0x023A/0x023B/0x023C).
  • Consumption/backup meter power from the load registers (0x021B/0x0232/0x0233 active, 0x0234/0x0235 reactive).

Writes

Both FC06 and FC16 supported. Read-only registers reject with exception code 7. Settings 0xE0xx writable. Control 0xDF00 area (power/reset/restore) is dangerous on the live unit: documented, not fired.

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