Register values look like large raw integers. What is wrong?

SunSpec integer meter models use companion scaling-factor registers to represent the implied decimal point. For example, multiply the 'w' value by 10 raised to the power of 'w_sf' to get watts. Always read the scaling-factor register in the same poll cycle as the measurement register, because scaling factors can change dynamically.

The gateway connects but all registers return zero or 0x8000 (not-implemented).

A value of 0x8000 (for int16) or 0xFFFF (for uint16) is the SunSpec not-implemented sentinel, meaning that register is not populated by the specific physical meter. Confirm the meter actually implements Model 202 by reading the 'id' register at offset 0 and checking that it returns 202. Also verify the correct base address offset is configured in the portal.

Cumulative energy totals 'totwhimp' and 'totwhexp' are not incrementing.

Confirm the meter CT orientation is correct for the split-phase ABN topology: reversed CTs cause the meter to attribute import as export. Also check that 'totwh_sf' is negative (which is typical), meaning the raw uint32 value must be divided rather than multiplied. Verify you are not reading the 32-bit register across two separate poll requests, which can introduce split-read errors.

The 'evt' register shows a non-zero value. What does this mean?

The 'evt' register is a 32-bit bitfield where each bit corresponds to a specific meter event or fault condition as defined in the SunSpec meter specification. A non-zero value indicates at least one active event. Cross-reference the set bits against the SunSpec meter event flag definitions to identify the specific condition. Set up a ModbusCloud portal alert on this register so any future fault is flagged immediately.

Free Modbus template: SunSpec Model 202 — split single phase (ABN) meter

Name: SunSpec Model 202 — split single phase (ABN) meter
Brand: SunSpec
SKU: 49bc8338-6adc-4d9d-98bf-aabedb0d390c

SunSpec Model 202 is an open-standard AC meter model defined by the SunSpec Alliance for split single-phase (ABN) installations. This Modbus TCP template reads the full set of per-phase and aggregate measurements: current, voltage (line-to-neutral and line-to-line), frequency, real power, apparent power, reactive power, power factor, and four-quadrant cumulative energy totals for both import and export. All numeric values are scaled by companion scaling-factor registers that must be applied at read time. The template also exposes the event bitfield for fault monitoring. Import it into your ModbusCloud portal to get immediate visibility into any SunSpec-compliant split-phase meter.

Registers (74)

74 read / 0 write

Name	Address	Function	Type	Unit	Access
id SunSpec model ID, value 202 identifies split single-phase meter.	0	FC03	uint16		R
l Length of this model block in 16-bit registers.	1	FC03	uint16		R
a Total AC current, sum of active phases, amperes.	2	FC03	int16	A	R
apha Phase A AC current, amperes.	3	FC03	int16	A	R
aphb Phase B AC current, amperes.	4	FC03	int16	A	R
aphc Phase C AC current, amperes.	5	FC03	int16	A	R
a_sf Scaling factor exponent applied to all current registers.	6	FC03	int16		R
phv Average line-to-neutral voltage across active phases, volts.	7	FC03	int16	V	R
phvpha Phase A line-to-neutral voltage, volts.	8	FC03	int16	V	R
phvphb Phase B line-to-neutral voltage, volts.	9	FC03	int16	V	R
phvphc Phase C line-to-neutral voltage, volts.	10	FC03	int16	V	R
ppv Average line-to-line voltage across active phase pairs, volts.	11	FC03	int16	V	R
phvphab Phase A to phase B line-to-line voltage, volts.	12	FC03	int16	V	R
phvphbc Phase B to phase C line-to-line voltage, volts.	13	FC03	int16	V	R
phvphca Phase C to phase A line-to-line voltage, volts.	14	FC03	int16	V	R
v_sf Scaling factor exponent applied to all voltage registers.	15	FC03	int16		R
hz Grid frequency, hertz.	16	FC03	int16	Hz	R
hz_sf Scaling factor exponent applied to the frequency register.	17	FC03	int16		R
w Total real (active) power across all phases, watts.	18	FC03	int16	W	R
wpha Phase A real power, watts.	19	FC03	int16	W	R
wphb Phase B real power, watts.	20	FC03	int16	W	R
wphc Phase C real power, watts.	21	FC03	int16	W	R
w_sf Scaling factor exponent applied to all real power registers.	22	FC03	int16		R
va Total apparent power across all phases, volt-amperes.	23	FC03	int16	VA	R
vapha Phase A apparent power, volt-amperes.	24	FC03	int16	VA	R
vaphb Phase B apparent power, volt-amperes.	25	FC03	int16	VA	R
vaphc Phase C apparent power, volt-amperes.	26	FC03	int16	VA	R
va_sf Scaling factor exponent applied to all apparent power registers.	27	FC03	int16		R
var Total reactive power across all phases, var.	28	FC03	int16	var	R
varpha Phase A reactive power, var.	29	FC03	int16	var	R
varphb Phase B reactive power, var.	30	FC03	int16	var	R
varphc Phase C reactive power, var.	31	FC03	int16	var	R
var_sf Scaling factor exponent applied to all reactive power registers.	32	FC03	int16		R
pf Average power factor across active phases, percent.	33	FC03	int16	Pct	R
pfpha Phase A power factor, percent.	34	FC03	int16	Pct	R
pfphb Phase B power factor, percent.	35	FC03	int16	Pct	R
pfphc Phase C power factor, percent.	36	FC03	int16	Pct	R
pf_sf Scaling factor exponent applied to all power factor registers.	37	FC03	int16		R
totwhexp Cumulative total real energy exported, watt-hours.	38	FC03	uint32	Wh	R
totwhexppha Cumulative phase A real energy exported, watt-hours.	40	FC03	uint32	Wh	R
totwhexpphb Cumulative phase B real energy exported, watt-hours.	42	FC03	uint32	Wh	R
totwhexpphc Cumulative phase C real energy exported, watt-hours.	44	FC03	uint32	Wh	R
totwhimp Cumulative total real energy imported, watt-hours.	46	FC03	uint32	Wh	R
totwhimppha Cumulative phase A real energy imported, watt-hours.	48	FC03	uint32	Wh	R
totwhimpphb Cumulative phase B real energy imported, watt-hours.	50	FC03	uint32	Wh	R
totwhimpphc Cumulative phase C real energy imported, watt-hours.	52	FC03	uint32	Wh	R
totwh_sf Scaling factor exponent applied to all real energy registers.	54	FC03	int16		R
totvahexp Cumulative total apparent energy exported, volt-ampere-hours.	55	FC03	uint32	VAh	R
totvahexppha Cumulative phase A apparent energy exported, volt-ampere-hours.	57	FC03	uint32	VAh	R
totvahexpphb Cumulative phase B apparent energy exported, volt-ampere-hours.	59	FC03	uint32	VAh	R
totvahexpphc Cumulative phase C apparent energy exported, volt-ampere-hours.	61	FC03	uint32	VAh	R
totvahimp Cumulative total apparent energy imported, volt-ampere-hours.	63	FC03	uint32	VAh	R
totvahimppha Cumulative phase A apparent energy imported, volt-ampere-hours.	65	FC03	uint32	VAh	R
totvahimpphb Cumulative phase B apparent energy imported, volt-ampere-hours.	67	FC03	uint32	VAh	R
totvahimpphc Cumulative phase C apparent energy imported, volt-ampere-hours.	69	FC03	uint32	VAh	R
totvah_sf Scaling factor exponent applied to all apparent energy registers.	71	FC03	int16		R
totvarhimpq1 Cumulative total reactive energy imported, quadrant 1, varh.	72	FC03	uint32	varh	R
totvarhimpq1pha Cumulative phase A reactive energy imported, quadrant 1, varh.	74	FC03	uint32	varh	R
totvarhimpq1phb Cumulative phase B reactive energy imported, quadrant 1, varh.	76	FC03	uint32	varh	R
totvarhimpq1phc Cumulative phase C reactive energy imported, quadrant 1, varh.	78	FC03	uint32	varh	R
totvarhimpq2 Cumulative total reactive energy imported, quadrant 2, varh.	80	FC03	uint32	varh	R
totvarhimpq2pha Cumulative phase A reactive energy imported, quadrant 2, varh.	82	FC03	uint32	varh	R
totvarhimpq2phb Cumulative phase B reactive energy imported, quadrant 2, varh.	84	FC03	uint32	varh	R
totvarhimpq2phc Cumulative phase C reactive energy imported, quadrant 2, varh.	86	FC03	uint32	varh	R
totvarhexpq3 Cumulative total reactive energy exported, quadrant 3, varh.	88	FC03	uint32	varh	R
totvarhexpq3pha Cumulative phase A reactive energy exported, quadrant 3, varh.	90	FC03	uint32	varh	R
totvarhexpq3phb Cumulative phase B reactive energy exported, quadrant 3, varh.	92	FC03	uint32	varh	R
totvarhexpq3phc Cumulative phase C reactive energy exported, quadrant 3, varh.	94	FC03	uint32	varh	R
totvarhexpq4 Cumulative total reactive energy exported, quadrant 4, varh.	96	FC03	uint32	varh	R
totvarhexpq4pha Cumulative phase A reactive energy exported, quadrant 4, varh.	98	FC03	uint32	varh	R
totvarhexpq4phb Cumulative phase B reactive energy exported, quadrant 4, varh.	100	FC03	uint32	varh	R
totvarhexpq4phc Cumulative phase C reactive energy exported, quadrant 4, varh.	102	FC03	uint32	varh	R
totvarh_sf Scaling factor exponent applied to all reactive energy registers.	104	FC03	int16		R
evt Meter event bitfield; non-zero bits indicate active fault or alarm conditions.	105	FC03	uint32		R

SunSpec Model 202 — split single phase (ABN) meter

Overview

Use cases

Installation

Things to watch for

Registers (74)

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