AlorAir Sentinel HD55 Dehumidifier

Product web page: https://www.alorair.com/product/alorair-sentinel-hd55

Manuals

• User Manual (5.98 MB)
• Specification (2.8 MB)
• Wiring Diagram (30 KB)
• Data Plate (148 KB)
• Parts List (1.02 MB)

Connector Block

Image captured from https://community.home-assistant.io/t/automate-alorair-sentinel-hd55-dehumidifier/306084/6

Remote

Parts

Part	Description
CPU	HC32F072 (clone of STM32F072) (datasheet)
LCD Controller	Holtek HT16C23
CAN Transceiver	3PEAK TPT1051V
EEPROM	BL24C02
Temperature sensor	Unknown (markings erased)
Humidity sensor	Unknown (no markings)

RJ-45 Pinout

Looking into the RJ-45 receptacle with the tab down, pin 1 is on the left.

Pin #	Description
1	N/C
2	N/C
3	N/C
4	CANL
5	CANH
6	N/C
7	VCC (5V0)
8	GND

J1 Programming Connector

Pin #	Description
1	nRST
2	VCC (3V3)
3	GND
4	SWCLK
5	SWDIO

CAN Bus

The dehumidifier and remote communicate using the CAN bus protocol at 50Kbps.

Currently, this decoding is based purely on using cantact-app, pushing buttons, and sending values. After I find a RJ45 breakout board, I'll monitor the actual data stream between the remote and the HD55.

Note that remote has several symbols that don't seem to be used. There is a tree symbol between the circled RH and house symbols, 'Time On' and 'Time Off' below the 'Draining' text, 'hr' text next to the percent symbol, a fan symbol to the right of the degrees Celsius symbol, and a bar graph in the lower right corner. The board has a footprint for a switch that is labeled 'WiFi new/old', so either the firmware supports the bar graph, or the same display is used on the WiFi version of the remote.

Tools

Tool	Description	Link	Comments
Adapter	CANable 0.4	https://canable.io/	The 0.4 is no longer available, use the 2.0
Software	cantact-app	https://github.com/linklayer/cantact-app	It's OK. Tried to use Cangaroo, never found the adapter

Notes

• Pressing the 'T' button will turn on the display backlight for 15 seconds or so, and also toggle the temperature display between Fahrenheit and Celsius. Unlike the other 6 buttons, it does not send a CAN message.
• The pump function (P button) is only available on the HDi90
• The temperature display is 0C (32F) minimum, 50C (122F) maximum, but temperatures over 37C (98F) do not display correctly, as there is no hundreds digit.
• The 7-segment display on the HD55 is supposed to display 'LO' if the temperature is under 0C (32F), but I have not found any bits that cause it to display on the remote.
• The up and down arrows send a 0x05 in byte 1, and a value in byte 2 that changes with each button press. Presumably it gets the initial value from the HD55/HDi90.

CAN Frame From Remote

CAN ID 0x123

Byte	Description
0	Always 0x01
1	Value Button Status 0x00 No button pressed 0x01 Power 0x02 Pump (sends 0x01 in byte 2) 0x03 Continuous (sends 0x01 in byte 2) 0x04 Mode (sends 0x01 in byte 2) 0x05 Up or down arrow (sends value in byte)
2	0x00 (except when button pressed, see above)
3	RH on remote (20% = 0x14, 99% = 0x63)
4	Temperature on remote (in C, 0x00 = 0C, 0x30 = 48C)
5	Always 0x00
6	Always 0x00
7	Always 0x00

CAN Frame To Remote

CAN ID 0x3b0

Byte	Description
0	RH value to display (20% = 0x14, 99% = 0x63)
1	Not used (?)
2	Not used (?)
3	Temperature to display (in C, 0x00 = 0C, 0x30 = 48C)
4	Not used (?)
5	Bit Description 0 (0x01) RH symbol on (indicates RH at dehumidifier) 1 (0x02) Circled RH + house on (indicates RH at remote) 2 (0x04) Unused (?) 3 (0x08) 'Cont.' on (indicates continuous operation) 4 (0x10) 'Draining' on (indicates drain pump is running) 5 (0x20) Unused (?) 6 (0x40) Display local RH and temp (set bit 1 also) 7 (0x80) Unused (?)
6	Not used (?)
7	Bit Description 0 (0x01) 'E4' (indicates A5/A6 condensate pump overflow) 1 (0x02) 'E5' (indicates refrigerant leak, may not apply to HD55/HDi90) 2 (0x04) 'HI' (next to 'RT', indicates temperature > 105) 3 (0x08) 'c0' (next to 'RT', indicates ?) 4 (0x10) 'E1' (indicates humidity sensor error on HD55/HDi90) 5 (0x20) Unused (?) 6 (0x40) Unused (?) 7 (0x80) Unused (?)