I installed the HomeHub but some registers return zero or errors. What to check?

Confirm you used UseCase 3 during HomeHub commissioning. Other wiring cases expose a smaller register set. If you installed UseCase 1 or 2, you need to rewire to UseCase 3 to get full access.

Which heat pump models work with this template?

Daikin lists Altherma 3 H HT, 3 H MT, 3 R, 3 R MT, and 3 M. Check the HomeHub installation manual for the current compatibility list. Altherma LT (1st generation) and older indoor units are not supported.

Room Target Temperature write has no effect on the indoor climate. What now?

The zone needs to be configured for external control in the Altherma installer menu. Without this, the heat pump ignores room setpoint writes and uses its own control logic.

Free Modbus template: Daikin Heating & Cooling

Name: Daikin Heating & Cooling
Brand: Daikin
SKU: a6f4f208-fdfa-42e1-a805-36d7fb7c6ae8

This ModbusCloud template controls Daikin Altherma 3 heat pumps through the Daikin HomeHub (EKRHH) interface over Modbus TCP (also supports Modbus RTU). It reads electrical power, flow and return temperatures, outside temperature, hot water storage temperature, flow rate, and heat pump error codes. Writes include operation mode, heating and cooling target flow temperatures, hot water storage target temperature, and room target temperatures. Requires Daikin MMI2 firmware 7.3.0 or higher.

Registers (42)

31 read / 20 write

Name	Address	Function	Type	Unit	Access
38 State Heatpump Operation Mode	37	FC04	int16		R
21 State Heatpump Error	20	FC04	int16		R
32 State Heatpump Electrical heater	31	FC04	int16		R
23 State Heatpump Error Sub Code	22	FC04	uint16		R
30 State Hot Water Circulationpump [PZ]	29	FC04	int16		R
31 State Heatpump Compressor [C]	30	FC04	int16		R
33 State Disinfection Operation mode	32	FC04	int16		R
35 State Defrost/Starting Operation mode	34	FC04	int16		R
36 State "Hot" Start	35	FC04	int16		R
37 State 3-Way Valve Heat+Cool/ Hot Water [3UV1]	36	FC04	int16		R
40 Actual Heatpump Flowtemperature after PlateHeatExchanger [PHE]	39	FC04	int16	°C	R
41 Actual Heatpump Flowtemperature after Backupheater [BUH]	40	FC04	int16	°C	R
42 Actual Heatpump Return Flowtemperature	41	FC04	int16	°C	R
43 Actual Hot Water Storage Temperature [tWW]	42	FC04	int16	°C	R
44 Actual Outsidetemperature [tAU]	43	FC04	int16	°C	R
49 Actual Heatpump Flow Rate [E]	48	FC04	int16	l/h	R
50 Actual External Roomtemperature	49	FC04	int16	°C	R
51 Actual Heatpump Electrical Power	50	FC04	int16	kW	R
52 State Hot Water Operation mode	51	FC04	int16		R
53 State Heating/Cooling Operation mode	52	FC04	int16		R/W
54 State Target Mainheating Flowtemperature Lower limit	53	FC04	int16	°C	R/W
55 State Target Mainheating Flowtemperature Upper limit	54	FC04	int16	°C	R/W
57 State Target Maincooling Flowtemperature Upper limit	56	FC04	int16	°C	R/W
56 State Target Maincooling Flowtemperature Lower limit	55	FC04	int16	°C	R/W
58 State Target Addheating Flowtemperature Lower limit	57	FC04	int16	°C	R/W
59 State Target Addheating Flowtemperature Upper limit	58	FC04	int16	°C	R
60 State Target Addcooling Flowtemperature Lower limit	59	FC04	int16	°C	R
61 State Target Addcooling Flowtemperature Upper limit	60	FC04	int16	°C	R
10 State Hot Water Storage Targettemperature	9	FC03	int16	°C	R/W
2 State Cooling Target Supply Flowtemperature	1	FC03	int16	°C	R/W
1 State Heating Target Supply Flowtemperature	0	FC03	int16	°C	R/W
3 Heatpump Operation Mode	2	FC06	int16		W
6 Heating Room Targettemperature	5	FC06	int16	°C	W
7 Cooling Room Targettemperature	6	FC06	int16	°C	W
4 Space Heating/Cooling Operation Mode	3	FC06	int16		W
9 Heatpump Quiet Mode Operation mode	8	FC06	int16		W
12 Hot Water Storage Operation mode	11	FC06	int16		W
13 Hot Water Storage Electrical Heater Operation mode	12	FC06	int16		W
63 Offset Weather Operation Mode Heating Supply Flow Targettemperature	63	FC06	int16	°C	W
65 Weather Operation mode HC2	64	FC06	int16		W
66 Offset Weather Operation Mode Heating Supply Flow Targettemperature HC2	65	FC06	int16	°C	W
67 Offset Weather Operation Mode Cooling Supply Flow Targettemperature HC2	66	FC06	int16	°C	W

Daikin Heating & Cooling

Overview

Key readings

Available commands

Use cases

Installation

Things to watch for

Registers (42)

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