Carlo Gavazzi EM330/EM340 energy meter

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

point	address (0-based)	type	scale	unit
V L1-N	0	I32LE	10	V
V L2-N	2	I32LE	10	V
V L3-N	4	I32LE	10	V
V L1-L2	6	I32LE	10	V
V L2-L3	8	I32LE	10	V
V L3-L1	10	I32LE	10	V
A L1	12	I32LE	1000	A
A L2	14	I32LE	1000	A
A L3	16	I32LE	1000	A
W L1	18	I32LE	10	W
W L2	20	I32LE	10	W
W L3	22	I32LE	10	W
VA L1	24	I32LE	10	VA
VA L2	26	I32LE	10	VA
VA L3	28	I32LE	10	VA
var L1	30	I32LE	10	var
var L2	32	I32LE	10	var
var L3	34	I32LE	10	var
V L-N sys	36	I32LE	10	V
V L-L sys	38	I32LE	10	V
W sys	40	I32LE	10	W
VA sys	42	I32LE	10	VA
var sys	44	I32LE	10	var
PF L1	46	I16	1000
PF L2	47	I16	1000
PF L3	48	I16	1000
PF sys	49	I16	1000
Phase sequence	50	I16	1
Hz	51	I16	10	Hz
kWh (+) TOT	52	I32LE	10	kWh
Kvarh (+) TOT	54	I32LE	10	kvarh
kW dmd	56	I32LE	10	W
kW dmd peak	58	I32LE	10	W
kWh (+) PARTIAL	60	I32LE	10	kWh
Kvarh (+) PARTIAL	62	I32LE	10	kvarh
kWh (+) L1	64	I32LE	10	kWh
kWh (+) L2	66	I32LE	10	kWh
kWh (+) L3	68	I32LE	10	kWh
kWh (+) t1	70	I32LE	10	kWh
kWh (+) t2	72	I32LE	10	kWh
kWh (+) t3	74	I32LE	1
kWh (+) t4	76	I32LE	1
kWh (-) TOT	78	I32LE	10	kWh
kvarh (-) TOT	80	I32LE	10	kvarh
kWh (-) PARTIAL	82	I32LE	1
Kvarh (-) PARTIAL	84	I32LE	1
kVAh TOT	86	I32LE	0.1	kVAh
kVAh PARTIAL	88	I32LE	0.1	kVAh
Run hour meter	90	I32LE	0.01	h
Run hour meter kWh (-)	92	I32LE	1
n.a.	94	I32LE	1
kWh (-) L1	96	I32LE	0.1	kWh
kWh (-) L2	98	I32LE	0.1	kWh
kWh (-) L3	100	I32LE	0.1	kWh
kWh (+) t5	102	I32LE	1
kWh (+) t6	104	I32LE	1
kWh (+) t7	106	I32LE	1
kWh (+) t8	108	I32LE	1
n.a.	110	I32LE	1
n.a.	112	I32LE	1
n.a.	114	I32LE	1
n.a.	116	I32LE	1
n.a.	118	I32LE	1
n.a.	120	I32LE	1
n.a.	122	I32LE	1
n.a.	124	I32LE	1
n.a.	126	I32LE	1
n.a.	128	I32LE	1
THD A L1	130	I32LE	100	%
THD A L2	132	I32LE	100	%
THD A L3	134	I32LE	100	%
THD V L-N sys	136	I32LE	100	%
THD V L1-N	138	I32LE	100	%
THD V L2-N	140	I32LE	100	%
THD V L3-N	142	I32LE	100	%
THD V L-L sys	144	I32LE	1
THD V L1-L2	146	I32LE	1
THD V L2-L3	148	I32LE	1
THD V L3-L1	150	I32LE	1
An	152	I32LE	1000	A
Run hour meter kWh (-)	246	I32LE	1
A n	248	I32LE	0.001	A
THD V L-N sys	250	I32LE	0.01	%
THD V L-L sys	252	I32LE	0.01	%
Run hour meter	254	I32LE	0.01	h
n.a.	256	I32LE	1
V L-N sys	258	I32LE	0.1	V
V L-L sys	260	I32LE	0.1	V
W sys	262	I32LE	0.1	W
VA sys	264	I32LE	0.1	VA
var sys	266	I32LE	0.1	var
PF sys	268	I32LE	0.001	PF
Phase sequence	270	I32LE	1
Hz	272	I32LE	0.1	Hz
kWh (+) TOT	274	I32LE	0.1	kWh
Kvarh (+) TOT	276	I32LE	0.1	kvarh
kWh (-) TOT	278	I32LE	0.1	kWh
kvarh (-) TOT	280	I32LE	0.1	kvarh
W dmd	282	I32LE	0.1	W
W dmd peak	284	I32LE	0.1	W
V L1-L2	286	I32LE	0.1	V
V L1-N	288	I32LE	0.1	V
A L1	290	I32LE	0.001	A
W L1	292	I32LE	0.1	W
VA L1	294	I32LE	0.1	VA
var L1	296	I32LE	0.1	var
PF L1	298	I32LE	0.001	PF
V L2-L3	300	I32LE	0.1	V
V L2-N	302	I32LE	0.1	V
A L2	304	I32LE	0.001	A
W L2	306	I32LE	0.1	W
VA L2	308	I32LE	0.1	VA
var L2	310	I32LE	0.1	var
PF L2	312	I32LE	0.001	PF
V L3-L1	314	I32LE	0.1	V
V L3-N	316	I32LE	0.1	V
A L3	318	I32LE	0.001	A
W L3	320	I32LE	0.1	W
VA L3	322	I32LE	0.1	VA
var L3	324	I32LE	0.1	var
PF L3	326	I32LE	0.001	PF
kWh (+) PARTIAL	328	I32LE	0.1	kWh
Kvarh (+) PARTIAL	330	I32LE	0.1	kvarh
kWh (+) L1	332	I32LE	0.1	kWh
kWh (+) L2	334	I32LE	0.1	kWh
kWh (+) L3	336	I32LE	0.1	kWh
kWh (+) t1	338	I32LE	0.1	kWh
kWh (+) t2	340	I32LE	0.1	kWh
kWh (+) t3	342	I32LE	1
kWh (+) t4	344	I32LE	1
kWh (-) PARTIAL	346	I32LE	1
Kvarh (-) PARTIAL	348	I32LE	1
kVAh TOT	350	I32LE	1
kVAh PARTIAL	352	I32LE	1
n.a.	354	I32LE	1
n.a.	356	I32LE	1
n.a.	358	I32LE	1
n.a.	360	I32LE	1
n.a.	362	I32LE	1
kWh (-) L1	364	I32LE	0.1	kWh
kWh (-) L2	366	I32LE	0.1	kWh
kWh (-) L3	368	I32LE	0.1	kWh
kWh (+) t5	370	I32LE	1
kWh (+) t6	372	I32LE	1
kWh (+) t7	374	I32LE	1
kWh (+) t8	376	I32LE	1
n.a.	378	I32LE	1
n.a.	380	I32LE	1
n.a.	382	I32LE	1
THD A L1	384	I32LE	0.01	%
THD V L1-N	386	I32LE	0.01	%
THD V L1-L2	388	I32LE	0.01	%
n.a.	390	I32LE	1
n.a.	392	I32LE	1
n.a.	394	I32LE	1
n.a.	396	I32LE	1
n.a.	398	I32LE	1
n.a.	400	I32LE	1
THD A L2	402	I32LE	0.01	%
THD V L2-N	404	I32LE	0.01	%
THD V L2-L3	406	I32LE	0.01	%
n.a.	408	I32LE	1
n.a.	410	I32LE	1
n.a.	412	I32LE	1
n.a.	414	I32LE	1
n.a.	416	I32LE	1
n.a.	418	I32LE	1
THD A L3	420	I32LE	0.01	%
THD V L3-N	422	I32LE	0.01	%
THD V L3-L1	424	I32LE	0.01	%
n.a.	426	I32LE	1
n.a.	428	I32LE	1
n.a.	430	I32LE	1
n.a.	432	I32LE	1
n.a.	434	I32LE	1
n.a.	436	I32LE	1
Version code	770	U16	1
Revision code	771	U16	1
kWh (+) TOT – INTeger part	1024	I32LE	1	kWh
kWh (+) TOT – DECimal part	1026	I32LE	0.001	kWh
kvarh (+) TOT – INTeger part	1028	I32LE	1	kvarh
kvarh (+) TOT – DECimal part	1030	I32LE	0.001	kvarh
kWh (-) TOT – INTeger part	1032	I32LE	1	kWh
kWh (-) TOT – DECimal part	1034	I32LE	0.001	kWh
kvarh (-) TOT – INTeger part	1036	I32LE	1	kvarh
kvarh (-) TOT – DECimal part	1038	I32LE	0.001	kvarh
kWh (+) TOT	1280	I64LE	0.001	kWh
Kvarh (+) TOT	1284	I64LE	0.001	kvarh
kWh (+) Partial	1288	I64LE	0.001	kWh
Kvarh (+) Partial	1292	I64LE	0.001	kvarh
kWh (+) L1	1296	I64LE	0.001	kWh
kWh (+) L2	1300	I64LE	0.001	kWh
kWh (+) L3	1304	I64LE	0.001	kWh
kWh (-) TOT	1308	I64LE	0.001	kWh
kWh (-) Partial	1312	I64LE	0.001	kWh
kvarh (-) TOT	1316	I64LE	0.001	kvarh
kvarh (-) Partial	1320	I64LE	0.001	kvarh
kVAh TOT	1324	I64LE	0.001	kVAh
kVAh Partial	1328	I64LE	0.001	kVAh
PASSWORD	4096	U16	1
Measuring system	4098	U16	1
Current transformer ratio	4099	U32LE	0.1
Voltage transformer ratio	4101	U32LE	0.1
Integration time for dmd power calculation	4112	U32LE	1
Ton (Ton time for pulse output square wave)	4114	U32LE	1
kWh per pulse relevant to digital out 1	4128	U32LE	1
kWh per pulse relevant to digital out 2	4130	U32LE	1
Display mode	4352	U16	1
Tariff management enabling	4353	U16	1
Home page selection	4354	U16	1
Measurement mode selection	4355	U16	1
Wrong connection (Installing help) management enabling	4356	U16	1
Wrong connection (installing help) status	4357	U16	1
THD calculation enabling	4358	U16	1
Secondary start-up current of the run hour meter	4359	U32LE	0.001	A
Tariff mode selection	4608	U16	1
Tariff number selection via serial comm.	4609	U16	1
RS485 instrument address	8192	U16	1
RS485 baud rate	8193	U16	1
RS485 parity	8194	U16	1
RS485 Stop bit	8195	U16	1
Max number of words readable with a single Modbus request	8196	U16	1
Reset of all partial and tariff meters, kWdmd and kWdmd peak.	16384	U16	1
Reset of total energy meters	16385	U16	1
Reset of run hour meter	16386	U16	1
Letter 1 (from SX)	20480	U16	1
Letter 2 (from SX)	20481	U16	1
Letter 3 (from SX)	20482	U16	1
Letter 4 (from SX)	20483	U16	1
Letter 5 (from SX)	20484	U16	1
Letter 6 (from SX)	20485	U16	1
Letter 7 (from SX)	20486	U16	1
Production year	20496	U16	1

link settings as documented (unverified): RTU; default 9600 8N1; unit ID 1; FC 03,04,06,08; Functions 03h and 04h have exactly the same effect and can be used indifferently. Maximum 50 registers can be read with a single request.

bench facts as documented (unverified)

terminals	A-, T
termination	120 ohm 1/2W 5% resistor between line B and A
shield/ground	Connect shield to GND on master side only
wiring notes	Suggested to use AWG24 balanced pair cable and add a third wire for GND connection.
max registers/read	50
response timeout	500 ms
inter-frame delay	40 ms
broadcast	supported
sentinel values	7FFFFFFFh (or EEE on display) for overflow
protocol notes	T null: Max interruption time during the request frame is 2.5 char
model register	11
serial register	20480
firmware register	770
identification notes	Model register is Carlo Gavazzi Controls identification code. Serial register is Letter 1 to Letter 7 starting at 5000h.
certifications	MID certification (PFA and PFB)
doc revision	Version 2 Revision 17 (July 05, 2021)

field reports — community-sourced, unverified (checked 2026-06-11)

Word order for 32-bit registers (INT32, UINT32) is LSW-first (Little Endian word swap), which requires word swapping in master configurations to avoid garbled or extremely large values. [source]
RS-485 polarity labeling uses A- for Data- and B+ for Data+, which is opposite to some standard Modbus master labeling (where A is D+ and B is D-), frequently causing communication failures due to swapped wiring. [source]
confirmed: comms defaults: baud rate 9600, parity None, stop bits 1, unit ID 1, RTU framing — confirmed by EM300 Series Modbus manual and multiple integration guides (e.g., TapHome, evcc, Loxone)
confirmed: Functions 03h and 04h have exactly the same effect and can be used indifferently — confirmed by EM300 Series Modbus manual Section 1.2
confirmed: Maximum 50 registers can be read with a single request — confirmed by EM300 Series Modbus manual Section 1.2.1 and 1.2.2
confirmed: Suggested to use AWG24 balanced pair cable and add a third wire for GND connection — confirmed by EM300 Series Modbus manual Section 1.3.1
confirmed: Connect shield to GND on master side only — confirmed by EM300 Series Modbus manual Section 1.3.1
confirmed: Termination: 120 ohm 1/2W 5% resistor between line B and A, and connect terminal A- with T in the last instrument — confirmed by EM300 Series Modbus manual Section 1.3.1
confirmed: Broadcast supported only with function code 06h using address 00h — confirmed by EM300 Series Modbus manual Section 1.2.5
confirmed: Response timeout (T response) is 500 ms, inter-frame delay (T delay) is 40 ms, and T null (max interruption time) is 2.5 char — confirmed by EM300 Series Modbus manual Section 1.3.2

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
coherence-checked — Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

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