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 unitunit, (including a grid-off / grid-on transition test on 2026-07-27).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. Legend: VERIFIED = decoded value matched physical reality live. INFERRED = best-effort from live values. UNCONFIRMED = needs a different operating state (off-grid / heavy charge) to prove.

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 (P02) - 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	(none)0x0238	(none)0x0239	x0.1 A. GRIDB/C CURRENT IS PHASE A ONLYlive in the documentedextended mapblock, 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. NONo total register: sum the three phases
load reactive power	(none)derive)	0x0234	0x0235	var. REACTIVE IS B/C ONLY (phasePhase A: derive)S=sqrt(P^2+Q^2) not given, derive
load apparent power	0x021C	(none)derive)	(none)derive)	VA. APPARENT IS PHASE A ONLY (B/C: derive S = sqrt(P^2 + Q^2))
load ratio	0x021F	0x0236	0x0237	%
load PF	0x021A	-	-	reads 0 (unpopulated) - derive PF = P / S

Other P02: state 0x0210 (enum),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 Icurrent 0x0102 (x0.1 A, signed, + charge / - discharge)signed), device temp 0x0103 (reads 0, dead), DC load 0x0104-0x0106 (0), PV1 0x0107-0x0109 (0, no PV), charge state 0x010B (enum, mislabelled on this model),0x010B, charge power 0x010E (W),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.

ExtendedGrid-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 - MODEL-SPECIFIC, NOT in the SRNE V1.7 doc

  Discovered by probing (the V1.7 doc stops at 0x0237). Read live in mains/bypass:

  addr	live value	INFERRED meaning	status
  0x0238	~12 (1.2 A)	per-phase current B (likely GRID current B)	UNCONFIRMED (= loadgrid I B in bypass)
  0x0239	~13 (1.3 A)	per-phase current C (likely GRID current C)	UNCONFIRMED
  0x023A	~1816	active power phase A	INFERRED (matches load P_A)
  0x023B	~267	active power phase B	INFERRED (matches load P_B)
  0x023C	~201	active power phase C	INFERRED (matches load P_C)
  0x023D	~2150	total or apparent (phase A ~2187 VA)	UNCONFIRMED
  0x023E	~297	unknown	UNCONFIRMED
  0x023F	~309	unknown	UNCONFIRMED

  IMPORTANT: in mains/bypass mode grid current = load current = (near) inverter current, so grid-side vs load-side registers are indistinguishable from this state. To confirm 0x0238/0x0239 as GRID current B/C (and+ grid power). This is how the 0x023A-Fextended meanings),block re-readwas duringidentified.

an
• LOAD-side (held through the transition, source-independent): load I/P/Q per phase (0x0219, 0x021B, 0x0230-0x0237).
• INVERTER-side (rose off-grid oras heavy-chargeit 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 where0x010B: 0 off-grid, load1 andon-grid.
inverter differ. Community SRNE docs found online map 0x0230+ differently (e.g. "R-phase voltage") because they are for other SRNE models; they do NOT apply to this three-phase ASP unit.

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

• Battery current sign: positive = discharge (doc says positive = charge - WRONG here).
• Machine state 0x02100x0210: 2 = 2running/mains-bypass, means3 RUNNING= (mains/bypass),off-grid. NOT the generic "initialization"initialization/soft-start". Only code 2 is verified.
• Power factor 0x021A reads 0. Derive PF = active (0x021B) / apparent (0x021C).
• Device temperature 0x0103 reads 0. Use heat-sink temps 0x0220 to 0x0222.
• Charge-state enum 0x010B reads "1 = quick charge" even at 94% SOC with 0 W charge power, so the generic charge-state enum does NOT match this model either.

For the OpenEMS driver (important)

• There is NO grid-power register, NO inverter-output-power register,and NO ESS/battery AC-power register, and NO total-power register on this unit.register. The only power registers are LOAD power per phase.
• Therefore the ESS SymmetricEss.ACTIVE_POWER must be DERIVED from battery DC power (0x0101 x 0x0102), the same V x I used for DcDischargePower.. Do NOT map load power 0x021B to ACTIVE_POWER: 0x021B(that is what the loads consume (verified 1803 W while the battery was idle/charging ~16 W), and it isloads, phase A only.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 active + reactive power per phase are available from the load registers (0x021B/0x0232/0x0233 active, 0x0234/0x0235 reactive) and can populate the ElectricityMeter power channels..

Writes

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