The alpha innotec Smart Home Interface (SHI) is a software interface built into the Luxtronik 2.1 heating and heat pump controller. It lets an energy management or smart home system read and write selected setpoints and parameters of the heat pump over Modbus TCP on port 502 — no extra hardware module is needed, only an Ethernet connection to the controller and the interface switched on in its menu.
This community template is built for a typical installation with one mixing circuit (MC1). It reads the system temperatures, controls the domestic hot water (DHW) and heating setpoints, blocks heating or DHW on demand, limits the power consumption of the heat pump (Smart Grid / §14a EnWG) and shows electrical and thermal energy.
Hardware connection
The network socket is the left socket at the bottom of the Luxtronik control unit (its exact position depends on the heat pump variant). A screened network cable, category 6, has to be laid through the unit during the electrical connection work; its RJ45 plug goes into this left socket. The other end connects to the same local network as the TapHome Core.
alpha innotec recommends protecting the controller against attacks and unauthorised access with a router or firewall and, in company or municipal networks, using a separate local network or VLAN. Modbus TCP is an older protocol with a low level of security — do not open port 502 to the internet; incoming connections from the internet are not required. Keep the controller software up to date.
Configuration
All settings are made on the controller display in the program area Service → Control panel. Some menu entries are only visible or adjustable with installer or customer service data access. If the entries below are not offered, raise the data access to Installer with the numeric code in the Service program area (“Determine data access” in the controller operating manual), and reset it to User after the work is finished.
Network settings
The controller must have a fixed address in the local network, because TapHome connects to it by IP address.
- Open Service → Control panel → DHCP.
- Choose one of the options:
- Client — the controller obtains its address from the DHCP server (router). In that case create a DHCP reservation for the controller in the router, so the address does not change.
- Off — the address is set manually. Then open Control panel → IP-address and enter IP, subnetmask, broadcast, gateway, DNS 1 and DNS 2 according to the local network, and save. The IP address must lie in the range of the network (for example gateway 192.168.2.1 and mask 255.255.255.0 allow 192.168.2.2 to 192.168.2.254, if not used by another device).
- Read the IP address of the controller on the IP-address screen and note it for TapHome.
When DHCP is set to Client (or Server), the values on the IP-address screen can only be read; they can be edited only with DHCP Off. Switching the DHCP option to Server or to Off always requires a restart (reset) of the controller.
Enabling the Smart Home Interface (Modbus TCP)
- Open Service → Control panel → Connectivity → Smart Home Interface.
- Select Settings and set ModBus TCP to On.
- Confirm with the check mark to save the setting.
alpha innotec instructs to deactivate the Smart Grid function of the controller when SHI is used — otherwise both functions may influence each other. Only one system should write to the SHI: when several SHI participants write the same data point, the controller reports error 816 and keeps SHI deactivated as long as the error is present.
The SHI menu is available in Luxtronik 2.1 software V3.90 and later. The overall heating mode and the extra DHW function used by this template need software V3.92 or later — update the controller software first if it is older.
Checking the connection on the controller
Under Smart Home Interface → status, the ModBus TCP line shows the state of the interface:
| Status | Meaning |
|---|---|
| Off | SHI is deactivated |
| Standby | SHI is activated, but no read or write has been detected for at least 10 minutes |
| Active | SHI is activated and a read or write was detected within the last 10 minutes |
Smart Home Interface → Received data lists every setpoint and parameter written via SHI (heating mode, heating setpoint and offset, DHW mode, setpoint and offset…). Values that have not been written or have been reset show ---. While SHI is active and a value has been written, an SHI symbol appears on the navigation screen of the controller; selecting it opens the received data overview.
Connection parameters
| Parameter | Value |
|---|---|
| Protocol | Modbus TCP |
| TCP port | 502 |
| IP address | address of the controller (see Network settings) |
| Modbus slave ID | 1 (template default) |
In TapHome, add the module from this template and enter the controller’s IP address and Modbus slave ID.
Device capabilities
System status and diagnostics
The module decodes the operating state of the heat pump (heating, DHW, standby and others) and the active heat generators — compressors VD1 and VD2 and auxiliary heaters ZWE1 to ZWE3. A controller error number is shown as an error on the module. Heating and DHW demand, enabled functions, the states of the brine pump and the heating, MC1 and DHW circulation pumps, the software version and operating hours are available as module attributes.
Temperatures
Separate temperature sensors show the return temperature and its setpoint, the return temperature at the buffer tank, the flow temperature, the outdoor temperature and its 24-hour average, and the heat source inlet and outlet temperatures (brine or air).
Domestic hot water
- DHW thermostat — current DHW temperature and setpoint; the setpoint can be written from TapHome. Minimum and maximum DHW temperature are attributes.
- DHW control mode — how TapHome influences DHW: no influence, setpoint, temperature offset or operating level. To write the DHW setpoint, set this mode to Setpoint first.
- DHW block — temporarily stops DHW heating, for example during an expensive electricity tariff.
- Extra DHW — starts a one-time DHW heating; the controller switches the function off by itself when it ends. Target temperature, duration and remaining time are attributes.
Heating
- Heating control mode — how TapHome influences the return temperature of the heating circuit: no influence, return setpoint, temperature offset or operating level. It applies only when the overall heating mode is set to individual (per circuit).
- Overall heating mode — individual control per circuit, a global offset or a global operating level for all circuits at once.
- Heating block — prevents heating operation.
Mixing circuit MC1
- MC1 flow thermostat — current and target flow temperature of mixing circuit MC1; the setpoint can be written from TapHome. Minimum and maximum flow temperature are attributes.
- MC1 control mode — no influence, flow setpoint, temperature offset or operating level.
Energy
- Electrical energy — total electrical energy consumed and current electrical power input.
- Heating thermal energy — heat output and thermal energy delivered for heating. Electrical energy for heating and DHW, thermal energy for DHW, total thermal energy and the predicted minimum power input are attributes.
Power limitation (Smart Grid / §14a)
The Power limit switch selects the limitation mode:
- No limit — normal operation.
- Soft limit (for example PV surplus) — the heat pump tries to stay below the set power; when heating or DHW falls below its limit temperature, it ignores the limit.
- Hard limit — limitation according to §14a of the German Energy Industry Act (EnWG).
The limit value (0–30 kW) is set with the Set power limit action. The current limit and the EVU1 and EVU2 signals are attributes.
TapHome polls the controller continuously, which keeps the SHI status Active. The Received data menu on the controller shows which written values are currently applied.
Troubleshooting
No data in TapHome
- Check that the controller is connected to the network and that the IP address in TapHome matches the IP-address screen.
- Check that ModBus TCP is set to On in Smart Home Interface → Settings.
- Check the slave ID in TapHome and that port 502 is not blocked by a firewall between TapHome and the controller.
SHI status shows Standby
- No read or write has reached the controller for 10 minutes — check the network connection and that the TapHome module is running.
Written setpoints are not applied or return to default values
- Open Received data — a value shown as
---has not been written or has been reset. - Check that the matching control mode (DHW, heating or MC1) is set to Setpoint before writing a temperature.
- Check that the Smart Grid function of the controller is deactivated.
Error 816 on the controller
- Several SHI participants write the same data point. Leave only one system writing to SHI; SHI stays deactivated while the error is present.
DHW temperature shows 75.0 °C
- This substitute value appears when the DHW sensor has failed, or when the system uses a thermostat input instead of a sensor. With a thermostat input, ignore this value.
A value reads 32767
- 32767 means that the register or function is not available — for example the function is not configured, the controller is switched off, or another mode has to be set first. The device then shows invalid data.
