Carlo Gavazzi WM20/WM30/WM40 power meter

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire. Word order and scaling are confirmed at the hardware-verified rung and at no rung below it.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale	unit
v_l1_n	80	F32LE	1	V
v_l2_n	82	F32LE	1	V
v_l3_n	84	F32LE	1	V
v_l_n_sum	86	F32LE	1	V
v_l1_l2	88	F32LE	1	V
v_l2_l3	90	F32LE	1	V
v_l3_l1	92	F32LE	1	V
v_l_l_sum	94	F32LE	1	V
a_l1	96	F32LE	1	A
a_l2	98	F32LE	1	A
a_l3	100	F32LE	1	A
a_n	102	F32LE	1	A
w_l1	104	F32LE	1	W
w_l2	106	F32LE	1	W
w_l3	108	F32LE	1	W
w_sum	110	F32LE	1	W
va_l1	112	F32LE	1	VA
va_l2	114	F32LE	1	VA
va_l3	116	F32LE	1	VA
va_sum	118	F32LE	1	VA
var_l1	120	F32LE	1	var
var_l2	122	F32LE	1	var
var_l3	124	F32LE	1	var
var_sum	126	F32LE	1	var
pf_l1	128	F32LE	1
pf_l2	130	F32LE	1
pf_l3	132	F32LE	1
pf_sum	134	F32LE	1
hz	136	F32LE	1	Hz
asymmetry_l_n_pct	138	F32LE	1	%
asymmetry_l_l_pct	140	F32LE	1	%
phase_sequence	142	F32LE	1
temperature	150	F32LE	1	°C
analogue_input	152	F32LE	1

link settings as documented (unverified): RTU; baud 9600/19200/38400/115200; FC 03,04,06,08,16,20,66; Supports broadcast mode on address 00h for write functions 06h and 10h.

bench facts as documented (unverified)

termination	To avoid errors due to the signal reflections or line coupling, it is necessary to terminate the input of the last instrument on the network, and also the reception of the Host.
shield/ground	The GND connection is optional if a shielded cable is used.
wiring notes	For connections longer than 1000 m, a line amplifier is necessary.
max registers/read	125
response timeout	1000 ms
inter-frame delay	2 ms
broadcast	supported
protocol notes	Typical answering time is 23 ms @ 9600 bps and <4 ms @ 115200 bps.
model register	300001
serial register	300033
firmware register	300001
FC 43 device ID	not supported
doc revision	4.0

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

For reliable communication and to read/write on all registers, third-party integration guides recommend setting the inter-frame delay (or request delay) to 300 ms or higher. [source]
Users have reported that the Ethernet/IP communication module (MC EI) for the WM30/WM40 drops connections randomly and fails to re-establish them without a power cycle. [source]
confirmed: Baud rates [9600, 19200, 38400, 115200] and framing [RTU] — confirmed by Carlo Gavazzi WM20-WM30-WM40 Communication Protocol manual
confirmed: Function codes [3, 4, 6, 8, 16, 20, 66] — confirmed by manual (where 20 is 14h 'Read record file' and 66 is 42h 'Read Special Registers')
confirmed: Broadcast mode on address 00h for write functions 06h and 10h — confirmed by manual
confirmed: Identification registers (firmware/model at 300001, serial at 300033) — confirmed by manual
confirmed: Physical notes regarding 1000m line amplifier, optional shield ground, and termination — confirmed by manual
confirmed: Typical answering times (23 ms @ 9600 bps, <4 ms @ 115200 bps) and max response timeout (1000 ms) — confirmed by manual
confirmed: Register map addresses (v_l1_n @ 80, v_l2_n @ 82, ..., analogue_input @ 152) — confirmed by manual

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.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

If your device isn't here, upload its register map. Generation is free, and the connector keeps the rung it earns under testing.

To prove a connector against your own device, order hardware verification. If it doesn't verify, you don't pay.

Platform builders can license the verified library: machine-readable maps, the firmware matrix, API access.