Free US shipping on orders $35+
Discord GitHub Contact
serin labs
Check your model Flash
The empty red CN105 serial port on a Mitsubishi indoor unit's control board, with the CN105 label and pins 1 and 5 marked in the silkscreen
CN105, on the control board of a Mitsubishi indoor unit.

Wiring reference: CN105 to Grove

Pin-for-pin wiring between the CN105 service port on a Mitsubishi indoor unit and the Grove HY2.0 connector on an M5Stack Atom S3 Lite or NanoC6. Every conductor, both housings, and the checks to make before power goes back on.

Crimp your own from the parts below, or buy the cable assembled and tested.

Wiring diagram

CN105 to Grove cable harness drawing Harness drawing. CN105 five-cavity housing left, Grove four-cavity housing right. Cavity 1, 12 volts, carries no wire. Black from cavity 2 GND to cavity 1 GND, red from 3 5V to 2 5V, white from 4 TX to 3 RX on GPIO 2, yellow from 5 RX to 4 TX on GPIO 1. CN105 · HVAC side PAP-05V-S · 5-way Grove · device side HY2.0-4P · 4-way 1 12V 2 GND 3 5V 4 TX 5 RX ▲ 1 matches the board silkscreen 1 GND 2 5V 3 RX GPIO 2 4 TX GPIO 1 Atom S3 Lite · NanoC6 leave cavity 1 empty Black Red White Yellow Power pair UART pair · 5 V logic · arrows lead the flow TX-to-RX is already built into the numbering; there is no crossover to make.

Scroll sideways to see the full diagram.

Wire CN105 Grove Carries
Black 2 · GND 1 · GND Ground reference
Red 3 · 5V 2 · 5V 5 V from the HVAC
White 4 · TX 3 · RX GPIO 2 HVAC → board
Yellow 5 · RX 4 · TX GPIO 1 Board → HVAC
none 1 · 12V — Leave empty

Check before you power it on

  1. Cavity 1 on the CN105 end is empty, and the ▲ lines up with the 1 on the board silkscreen.
  2. Black and red are not swapped; reversed power is the one mistake that damages a board.
  3. Unit power is off at the breaker before the connector goes in or comes out.
The orange Serin CN105-to-Grove cable plugged into the CN105 port on a Mitsubishi MVZ-A18AA7 ducted air handler control board
The finished cable seated in a real CN105 port, here on a Mitsubishi MVZ-A18AA7 ducted air handler.
The CN105-to-Grove cable plugged into the CN105 port on the control board of a Mitsubishi wall unit
The same connection on a wall unit, where the board sits beside it.

Pinout reference

CN105 · JST-PAP-05V-S

Pin Signal Description
112VNot used
2GNDGround
35V5V Power
4TXData output from HVAC (5V logic)
5RXData input to HVAC (5V logic)

Grove · HY2.0-4P Atom S3 Lite, NanoC6

Pin Signal Description
1GGround (connects to ESP32 GND)
25V5V Power (connects to ESP32 5V/VCC)
3G2RX (connects to ESP32 UART RX pin)
4G1TX (connects to ESP32 UART TX pin)

Build your own

Two connector housings and four conductors. Crimp the pinout above into these:

The parts list covers the boards these connect to.

Safety

Turn off power to the indoor unit at the breaker, not just at the remote, before connecting or disconnecting any cable, and leave it off until the cover is back on. CN105 is the only connector that needs to be handled; the rest of the control board carries line voltage.

A five-way JST PAP-05V-S connector at the top and a four-way Grove HY2.0-4P connector at the bottom, joined by four wires: yellow, white, red, and black

References

Ready-made alternative

Buy the cable assembled

The same harness, built and electrically tested, from $8, in 20 cm and 50 cm. Or take the Serin Controller, which is an ESP32 board with this cable already attached, from $35.

CN105 Cable Serin Controller