Northern Design Cube 400 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
kwh	514	U32BE	1	kWh
kvah	516	U32BE	1	kVAh
kvarh_inductive	518	U32BE	1	kvarh
kvarh_capacitive	520	U32BE	1	kvarh
import_kvarh	522	U32BE	1	kvarh
export_kwh	524	U32BE	1	kWh
export_kvarh	526	U32BE	1	kvarh
hours_run	528	U32BE	1	h
system_kw	2816	I16	1	kW
system_kva	2817	I16	1	kVA
system_kvar	2818	I16	1	kvar
system_pf	2819	I16	0.001
frequency	2820	I16	0.1	Hz
phase_1_volts	2821	I16	1	V
phase_1_amps	2822	I16	1	A
phase_1_kw	2823	I16	1	kW
phase_2_volts	2824	I16	1	V
phase_2_amps	2825	I16	1	A
phase_2_kw	2826	I16	1	kW
phase_3_volts	2827	I16	1	V
phase_3_amps	2828	I16	1	A
phase_3_kw	2829	I16	1	kW
phase_1_pf	2830	I16	0.001
phase_2_pf	2831	I16	0.001
phase_3_pf	2832	I16	0.001
ph1_ph2_volts	2833	I16	1	V
ph2_ph3_volts	2834	I16	1	V
ph3_ph1_volts	2835	I16	1	V
neutral_current	2836	I16	1	A
phase_1_kva	3072	I16	1	kVA
phase_2_kva	3073	I16	1	kVA
phase_3_kva	3074	I16	1	kVA
phase_1_kvar	3075	I16	1	kvar
phase_2_kvar	3076	I16	1	kvar
phase_3_kvar	3077	I16	1	kvar
v1_thd	4352	U16	0.1	%
v2_thd	4353	U16	0.1	%
v3_thd	4354	U16	0.1	%
i1_thd	4355	U16	0.1	%
i2_thd	4356	U16	0.1	%
i3_thd	4357	U16	0.1	%

link settings as documented (unverified): RTU; baud 4800/9600/19200; FC 03,04,06,08,16; Modbus RTU/JBUS, 16-Bit CRC

⚠ The Cube400 is intended for connection to dangerous voltages giving a risk of electric shock. Refer to the safety/installation instructions in the Cube400 Installation Guide before connecting the communications. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	Rising clamp, max wire 4mm2
termination	Two 120 Ohm resistors recommended
isolation	3.5kV (1 minute) RS485 Port from all other circuit
shield/ground	Shield should be connected to ground at the host (PC) only. The cable shield should not be used as the 0V connection.
wiring notes	3-Pairs of terminals, internally shorted, are provided for convenience.
max registers/read	20
response timeout	250 ms
inter-frame delay	5 ms
broadcast	supported
protocol notes	Exception codes 1 and 2 are supported.
model register	3590
firmware register	3592
identification notes	Meter Type is at register 3591.
power	Internally supplied from Cube400 Auxiliary. Requires additional 1W max
doc revision	Revision 5, July 2016

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

When attempting to read a non-existent register (e.g., register 2815 / 0x0AFF) over Modbus TCP, the device echoes back the exact request bytes instead of returning a standard Modbus exception response, causing an 'Incorrect PDU length' error in the master. [source]
confirmed: Baud rates [4800, 9600, 19200], framing [RTU], function codes [3, 4, 6, 8, 16], Modbus RTU/JBUS, 16-Bit CRC — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Control warning regarding dangerous voltages and safety instructions — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Document revision 'Revision 5, July 2016' — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Identification registers (model at 3590, type at 3591, firmware at 3592) — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Physical specifications (3.5kV isolation, 3-pairs of internally shorted terminals, shield ground recommendations, rising clamp terminals up to 4mm2, and two 120 Ohm resistors recommended) — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Power requirements (internally supplied from auxiliary, additional 1W max) — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Quirks (broadcast supported, 5ms inter-frame delay, max 20 read registers, exception codes 1 and 2 supported, 250ms response timeout) — confirmed by Cube400 Modbus Comms Manual REV5
confirmed: Register map summary (energy registers starting at 514, instantaneous values starting at 2816, additional instantaneous values starting at 3072, and THD values starting at 4352) — confirmed by Cube400 Modbus Comms Manual REV5

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.