Chint DTSU666 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
uab	8192	F32BE	1	V
ubc	8194	F32BE	1	V
uca	8196	F32BE	1	V
ua	8198	F32BE	1	V
ub	8200	F32BE	1	V
uc	8202	F32BE	1	V
ia	8204	F32BE	1	A
ib	8206	F32BE	1	A
ic	8208	F32BE	1	A
pt	8210	F32BE	1	W
pa	8212	F32BE	1	W
pb	8214	F32BE	1	W
pc	8216	F32BE	1	W
qt	8218	F32BE	1	var
qa	8220	F32BE	1	var
qb	8222	F32BE	1	var
qc	8224	F32BE	1	var
pft	8234	F32BE	1
pfa	8236	F32BE	1
pfb	8238	F32BE	1
pfc	8240	F32BE	1
freq	8260	F32BE	1	Hz
imp_ep	4126	F32BE	1	kWh
imp_ep_a	4128	F32BE	1	kWh
imp_ep_b	4130	F32BE	1	kWh
imp_ep_c	4132	F32BE	1	kWh
net_imp_ep	4134	F32BE	1	kWh
exp_ep	4136	F32BE	1	kWh
exp_ep_a	4138	F32BE	1	kWh
exp_ep_b	4140	F32BE	1	kWh
exp_ep_c	4142	F32BE	1	kWh
net_exp_ep	4144	F32BE	1	kWh

link settings as documented (unverified): RTU; default 9600 8N1; unit ID 1; FC 03,16; The factory default baud rate is 9600bps, n.8.1. The communication address of Modbus protocol is 01 (1 ~ 247).

bench facts as documented (unverified)

terminals	RS485 Terminal A (24), Terminal B (25)
A/B polarity	A (+), B (-)
termination	120 ohm resistor at start and end terminals if distance is over 150 meters
connector	Screw terminals
wiring notes	Current cable terminal conductor cross-sectional area range <= 16 mm2, RS485 cable terminal 0.25-1 mm2
protocol notes	Single-precision floating point adopts standard IEEE754 format, total 32 bit (4 word). The single-precision floating point mode is assumed to be ABCD (high type in the front, low byte behind).
firmware register	0000H
identification notes	0000H REV. Software Version
power	Power consumption of the voltage circuit <= 1.5W and 6VA. Power consumption of the current circuit: Ib < 10A <= 0.2VA, Ib >= 10A <= 0.4VA
environment	Regulated working temperature range: -10℃～+45℃; Limited working temperature range: -25℃～+75℃; Relative humidity (Annually average): <= 75% RH; Atmospheric pressure: 63.0kPa～106.0kPa
accuracy	Active class 0.5S, reactive class 2 (or Active class 1, Reactive class 2 depending on model)
certifications	IEC 61010-1:2010, IEC 61326-1:2013
doc revision	ZTY0.464.1448V2

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

The DTSU666 meter has an 'autocorrecting' CT function (enabled by default via parameters J-1 and J-2) that attempts to detect and correct CTs placed on the wrong phase. However, it only runs once upon first power-on. If an installer corrects a CT placement error later, the meter retains the old 'correction' internally, causing incorrect readings. Installers are advised to disable this function by setting J-1 and J-2 parameters to 0. [source]
When integrating the DTSU666 with Loxone, users report that the 'Byte Order' checkbox must be selected for all sensors to parse the Modbus data correctly, though some firmware versions may work without it. [source]
confirmed: comms.baud_rates: [1200, 2400, 4800, 9600, 19200] — confirmed by Chint DTSU666 Datasheet and User Manuals which list these baud rates.
confirmed: comms.default_baud: 9600 — confirmed by Chint DTSU666 User Manuals stating the factory default baud rate is 9600 bps.
confirmed: comms.default_unit_id: 1 — confirmed by Chint DTSU666 User Manuals stating the default communication address is 01.
confirmed: facts.certifications: IEC 61010-1:2010, IEC 61326-1:2013 — confirmed by Chint DTSU666 User Manuals stating compliance with these standards.
confirmed: facts.doc_revision: ZTY0.464.1448V2 — confirmed by Chint DTSU666 User Manuals carrying the document code ZTY0.464.1448.
confirmed: facts.environment: Regulated working temperature range: -10℃～+45℃; Limited working temperature range: -25℃～+75℃; Relative humidity (Annually average): <= 75% RH; Atmospheric pressure: 63.0kPa～106.0kPa — confirmed by Chint DTSU666 User Manuals.
confirmed: facts.physical: RS485 Terminal A (24), Terminal B (25) — confirmed by Chint DTSU666 User Manuals and wiring diagrams.
confirmed: facts.power: Power consumption of the voltage circuit <= 1.5W and 6VA. Power consumption of the current circuit: Ib < 10A <= 0.2VA, Ib >= 10A <= 0.4VA — confirmed by Chint DTSU666 User Manuals.

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.