[!Warning] Messing about inside an air-con can be dangerous (mains voltage) and can damage the unit. Take appropriate precautions and proceed at your own risk.
Important: X403 is a non-isolated version of S21. If you wire to X403, your Faikin can be at live potential and must be safely enclosed. Never wire anything with power on. See X403.

This page collects comments and practical advice on wiring, leads, plugs/sockets, and connector types.

---

Pre-made cables and drawings

Pre-made cables are available from Faikin Australia.

There are currently seven known connector combinations. For convenience, these are labelled Type A through Type G (the lettering is arbitrary and not meaningful).

If you’d like to make your own cables, here are the technical drawings (by Andrew, Faikin Australia):

Type A Type B Type C Type D Type E Type F Type G

---

Connecting options

There are multiple ways to connect a Faikin to a Daikin indoor unit:

• S21: Primary connection method.
• X403: Similar to S21 but not electrically isolated (dangerous if not enclosed correctly).
• X50A: Requires X35A for power (two connectors used).
• CN_WIRED: Newest supported connector/protocol.

Jump to:

• S21 connector
• X403 connector
• X50A connector
• CN_WIRED connector

---

S21 connector

The main connection to the Faikin module is S21, which will usually have 4 or 5 wires, wired 1:1 from S21 to Faikin.

The official Daikin S21 cable has one set of colours. There is also a generic cable (often supplied with Faikin on Tindie) with different colours. The cables from Australia are different again.

Pin	Daikin colour	Generic cable colour	Meaning
1	Brown	Orange	5V (not always connected)
2	Red	Blue	Tx from aircon (5V logic)
3	Orange	Yellow	Rx to aircon (5V logic; most models accept 3.3V)
4	Yellow	Red	12V/14V (powers Faikin)
5	Blue	Black	GND

---

S21 cabling notes

Different Daikin models use different physical connectors for the S21 interface:

• Type A uses a JST EH connector (2.5 mm pitch). On the indoor unit side this is typically JST EHR.
• Type B uses a smaller JST PAP connector (2.0 mm pitch) on the indoor unit side.

On the Faikin board side, the connector is JST EH male (5-way). Pre-made cables are available through Faikin Australia.

If you have an existing Daikin Wi-Fi module on a cable with a 5-pin S21 plug, it can be as simple as swapping that module for the Faikin. In other cases you may need to make/obtain a cable and connect to the indoor unit PCB. In some scenarios it is possible to use both the Faikin and Daikin Wi-Fi unit at the same time.

Key points:

• S21 is one-to-one wired: Pin 1 → Pin 1, etc.
• Pin 5 is ⏚ (GND).

Connector variants you may encounter:

• JST EHR (EH series) on many older models (Type A, 2.5 mm pitch)
• JST PAP on some newer models (Type B, 2.0 mm pitch)

Quick-and-dirty option: jumper wires

It is often possible to use jumper wires as a quick connection method.

Special case: X10A used as “S21-like”

If using an X10A connector, pin 4 (12V) may not be present, but pin 1 (5V) can provide enough power. In that case run pin 1 (5V) from the X10A to pin 4 on the Faikin (12V input). The Faikin can run from 4V to 36V on pin 4.

More experience is scattered through discussions/issues, and on the list of confirmed working air con units.

Adapter leads exist (e.g. PAP → EH such as EKRS21), and it’s also possible to buy pre-crimped leads (PAP/EH) and insert into housings.

JST crimp tools are often expensive; alternatives like ENGINEER PA-09 or iCrimp IWS-3220M should be suitable.

Part	Manuf. P/N	RS	DigiKey	Comment
Female Connector (EH)	EHR-5	311-6237	455-1003-ND	Used on the Faikin and older S21 connectors; probably the part you will want some of
Female Crimp Terminal (EH)	SEH-001T-P0.6 or BEH-001T-P0.6	123-5946 (min qty 250) 311-6439 (min qty 100)	455-1042-1-ND
12" EH Lead	ASEHSEH22K305		455-3104-ND
6" EH Lead	ASEHSEH22K152		455-3103-ND
Female Connector (PAP)	PAP-05V-S		455-1489-ND	Used on some newer S21 connectors (Type B)
Female Crimp Terminal (PAP)	SPHD-001T-P0.5		455-1325-1-ND
12" PAP Lead	APAPA22K305		455-3086-ND
6" PAP Lead	APAPA22K152		455-3085-ND
Jumper wire				Amazon and many others

Another approach is jumper wires using header pins/sockets:

---

X403 connector

[!Warning] This connector is known to have high voltages present. Use at your own risk!

The proper way to interface this connector to your Faikin is with a Daikin S21 adapter board, as S403/X403 is not isolated. This link has more details.

Some have found success and others have had issues using S403.

Two S403 socket types exist

Type D (JST XAP)

Seen in more modern split systems. Named Type D

Type E (JST PBVP-10, but a modified JST PAP also fits)

Seen in more modern split systems. Named Type E

---

X50A connector

For X50A you need power from X35A as well. More information can be found here.

Two X50A socket types exist

Type F (Molex Micro-Lock (X50A) and XHP (X35A))

Often seen in mor modern ducted units and ceiling cassette systems. Named Type F

Type C (JST ZHR (X50A) and XHP (X35A))

Often seen in ducted systems. Named Type C

X35A sockets are the same on both variations. Both cables are available from Faikin Australia.

---

CN_WIRED connector

This is the newest supported protocol and there may be issues or unsupported features. This protocol may need a pull-up on the Data - To Faikin pin (Faikin pin 2), which is present on newer Faikins. There is an issue with details and current status of CN_WIRED.

CN_WIRED cabling

From a single sample the following is true: CN_WIRED is a JST PH Series connector and is wired to a Faikin as shown below. Don’t worry that CN_WIRED voltage is greater than 12V, Faikin supports 4–36V on its 12V pin.

Faikin Pin	Meaning	CN_WIRED Pin
1	5V (used to translate logic levels)	1
2	Data → Faikin	4
3	Data ← Faikin	2
4	12V (powers Faikin)	5
5	GND	3

Once connected, be sure to disable Do not try CN_WIRED protocol (nocnwired) in settings. This is required for Faikin to detect a CN_WIRED connected aircon.

Note: Pin-1 location may differ depending on the board/connector orientation.