Smart meter wiring made simple
Which Eastron meter Australia actually uses, its terminal map, and the three mistakes that cause ~90% of meter issues: CT direction, A/B swap, and the wrong RS485 port.
Start here — the Deye manual draws the wrong meter
The Deye All-in-One manual’s “System connection diagram for the Eastron meter” (printed p.24) shows an Eastron SDM230: a direct-connect meter, mains in on terminals 1/3 and out on 2/4, RS485 on 5/6/7. Australia does not use it. Confirmed with Deye application engineering, 3 September 2026.
What Suncloud ships is CT-operated — the mains never enters the meter at all. It takes a voltage reference and reads current through a clip-on CT:
| Site | Part | What is in the box |
|---|---|---|
| Single phase | SDM120CTM-40mA + ESCT-TA16 | 1 meter, 1 CT |
| Three phase | SDM630MCT-40mA + ESCT-TA16 | 1 meter, 3 CTs |
Same CT on both: 120 A primary, 40 mA secondary, split core, 16.3 mm aperture, 1 m white/black leads. A 5 A, 1 A or 333 mV CT will not read on either meter.
Manuals: SDM120 series · SDM630MCT 40mA + ESCT-TA16.
Terminal maps
SDM120CTM — single phase
| Terminal | What lands on it |
|---|---|
| 1 · 2 | CT secondary. S1 (white) to 1, S2 (black) to 2 |
| 3 · 4 | Voltage reference: 3 = N, 4 = L. Also what powers the meter |
| 5 · 6 · 7 | Pulse outputs — not used |
| 8 · 9 · 10 | RS485: 8 = G, 9 = B−, 10 = A+ |
SDM630MCT — three phase
| Block | Terminals | Wiring |
|---|---|---|
| Voltage input | 1–4 | 1 = N, 2 = L3, 3 = L2, 4 = L1 |
| Current input | 15–20 | L3 → 15/16 · L2 → 17/18 · L1 → 19/20 |
| Each CT | S2 / S1 | black to the odd terminal, white to the even |
| Auxiliary supply | 5 · 6 | 5 = L, 6 = N, 85–275 V a.c. — required |
| RS485 | 12 · 13 · 14 | 12 = GND, 13 = B, 14 = A |
The three-phase meter needs its own supply on 5 and 6. The single-phase one does not — it powers itself off its voltage reference. It is the step people miss when they have only ever fitted an SDM120.
On the inverter, set Advanced Function → Meter Select to Eastron-1P or Eastron-3P,
and the CT ratio to 120. The list also holds CHNT-1P / CHNT-3P — a different pinout,
and not the meter we ship.
If the readings in DeyeCloud look wrong — import and export swapped, battery charging from the grid when it shouldn’t, or zero metering data — it’s almost always one of three things.
1. CT direction
The current transformer is directional — both the way it faces and which way the two CT leads land have to be right.
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Eastron ESCT-TA16: the case is marked P1 → P2 and the polarity dots sit on P1 and on the white lead. Clamp it on the grid live with P1 facing the grid, so the arrow points away from the grid, towards the inverter.
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The Deye inverter’s own CT (the one that lands on the inverter’s CT input, not on the meter): arrow towards the inverter, white lead left, black right.
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Exception — SUN-10/12K SG02LP1 (single-phase LV): keep the arrow towards the inverter, but reverse the leads — white on the right, black on the left.
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Never leave a CT secondary open-circuit with the primary live. Land both leads first.
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Symptom: import and export are reversed — the system “exports” when the house is actually drawing power.
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Fix: flip the CT 180° so the arrow faces the inverter, or swap the white/black leads, whichever brings the reading the right way round.
2. RS485 A/B swap
The meter talks to the inverter over RS485 (two data wires, A and B). Swapping them kills communication.
- Symptom: no meter data at all, or a meter-communication fault.
- Fix: confirm A→A, B→B between the meter and the inverter’s meter port. If unsure, try swapping the two — it won’t damage anything.
3. Wrong port
Deye hybrids have two RS485 ports — one for the battery BMS and one for the meter. Landing the meter on the BMS port (or vice-versa) means neither talks.
- Symptom: meter and/or battery shows offline despite correct wiring.
- Fix: check the inverter’s port legend — meter to the meter/CT port, battery comms to the BMS port.
Verify it
Single phase. In DeyeCloud, draw a known load (kettle/oven) and watch the flow: consumption = import (positive), PV surplus = export (negative).
Three phase. Load one phase at a time and watch it move on its own — kettle on L1, L1 current rises, L2 and L3 sit still. Then L2, then L3. A CT on the wrong phase still reads; it just reads the wrong power, often negative on one line, and nothing on the screen says so. This test is the only reliable way to catch a crossed pair.
If the SDM120 CT meter won’t communicate at all, see SDM120 CT meter ID fix.
