inetbox2mqtt on Venus OS

Introduction

This is a fork of the original inetbox2mqtt Truma iNet Box emulator found at https://github.com/mc0110/inetbox2mqtt, created for the purpose of porting it to standard CPython.

The original inetbox2mqtt was implemented in MicroPython and is intended to run on a dedicated microcontroller board such as an ESP32. Since some RV installations already run Victron Cerbo GX with Venus OS on a standard Raspberry Pi, it is beneficial to use the same platform to run inetbox2mqtt.

This fork ports inetbox2mqtt from MicroPython to standard CPython for execution on a Raspberry Pi. The Web OS is no longer required, as the configuration file (etc/inetbox2mqtt) can now be edited directly via SSH. The encrypted configuration previously generated by the Web OS has been replaced with a plain-text configuration file.

Since Venus OS manages its own network connectivity, all network configuration code has been removed from connect.py.

The status LED functionality previously used for LIN bus debugging has also been disabled, as users can now access the log files directly.

Additionally, a Node-RED dashboard for controlling the Truma Combi heater is included under node-red/caravan-dashboard.json.

Prerequisites

This setup has been tested on a Raspberry Pi 3 running the Victron Venus OS Large version with Node-RED enabled. This guide assumes you have a working Venus OS installation and are familiar with Victron Cerbo GX, Venus OS, and Node-RED concepts.

It also assumes you have configured SSH root access to Venus OS.

For general Venus OS Large and Node-RED setup instructions, visit https://www.victronenergy.com/live/venus-os:large.

Hardware Setup

This setup uses a TJA1020 TTL UART to LIN bus converter. To simplify wiring and avoid interfering with Venus OS operations, the onboard serial port of the Raspberry Pi is not used. Instead, an FT232RL-compatible USB-to-serial converter is recommended. The voltage jumper on the FT232RL board should be set to 3.3V to ensure compatibility with the TJA1020 module.

The electrical connections are described in the following table:

FT232RL Pin	TJA1020 Pin	LIN Bus	Power Supply
GND	GND	GND
RXD	TX
TXD	RX
	LIN	LIN
	12V		+12V fused 100mA

The images below display the completed setup, where the TJA1020 and FT232RL modules are connected together on a prototyping stripboard:

The following image shows the LIN bus RJ12 connector pinout:

The RJ12 connecter can be plugged into any free LIN port on the CP Plus or Truma Combi.

Further details are provided in the original inetbox2mqtt electrics guide and this similar project.

Installation

Follow these steps for installation:

1. Clone this repository to /data/inetbox2mqtt.

2. Create symbolic link for the service startup script:

   ln -s /data/inetbox2mqtt/service/inetbox2mqtt /opt/victronenergy/service/

3. Create symbolic link for the temperature reporting script - enables displaying the room and water temperatures in the Victron GUI V2 as well as VRM portal:

   ln -s /data/inetbox2mqtt/service/RpiTemperature /opt/victronenergy/service/

4. Create symbolic link to the udev rules file for ignoring FT232R_USB_UART devices. This prevents Venus OS from automatically using the LIN bus serial port:

   ln -s /data/inetbox2mqtt/etc/udev/rules.d/zz-serial-starter-override.rules /etc/udev/rules.d/

5. Create symbolic link to the inetbox2mqtt configuration file:

   ln -s /data/inetbox2mqtt/etc/inetbox2mqtt /etc/

6. Edit the configuration parameters in /etc/inetbox2mqtt:

   • Use localhost and port 1883 for connecting to the local MQTT server provided by Venus OS.
   • Set the serial device path to your FTDI-compatible adapter, e.g.: /dev/serial/by-id/usb-FTDI_FT232R_USB_UART_00000000-if00-port0

7. Additional services—such as bt-daemon (for enabling RFCOMM Bluetooth devices) and gpio-daemon (for allowing GPIO control by non‑root users)—are available at https://github.com/microfarad-de/nastia-server/tree/venus-os. These scripts are required for the fridge controller Node‑RED flow described at https://github.com/microfarad-de/fridge-controller.

Venus OS Configuration

Before starting the inetbox2mqtt service, configure the following in Venus OS:

1. Enable MQTT access via the Venus GUI at http://<rpi_ip_address> under Settings > Services.

2. Enable Node-RED under Settings > Venus OS Large features. This will provide the web interface to control your Truma Combi.

3. Enable classic Bluetooth for RFCOMM communication (optional, but required for the fridge controller at https://github.com/microfarad-de/fridge-controller), update /etc/bluetooth/ble.conf by changing the value of ControllerMode from le to dual:

   ControllerMode = dual
   

4. Disable vesmart-server service, which isn't essential and interferes with RFCOMM communication, by calling the following command then rebooting:

   touch /opt/victronenergy/service-templates/vesmart-server/down

5. Enable Node-RED access via plain HTTP by setting uiHost: "0.0.0.0" in the user settings. This is required for avoiding periodic connectivity loss when running the Node-Red dashboard as a home screen app:

   ln -s /data/inetbox2mqtt/node-red/settings-user.js /data/home/nodered/.node-red/

Automatic Installation Script

All the required Venus OS changes described in the previous sections can be applied automatically by calling the automated installation script bundled in this repository:

./install.sh

This script will perform the following actions:

1. Create all of the required symbolic links for both inetbox2mqtt.

2. Create additional symbolic links for the nastia-server automation toolbox (https://github.com/microfarad-de/nastia-server).

3. Apply any required Venus OS system file patches.

This script has been tested with Venus OS version 3.67.

Bring-Up

Once the hardware is connected, you will need to pair the Truma CP Plus control panel with the new setup.

1. Reboot the Raspbery Pi by calling reboot

2. Stop the inetbox2mqtt service:

   svc -d /service/inetbox2mqtt

3. Disconnect any existing iNet Box, and navigate to RESET > PR SET on your CP Plus to initialize it without the iNet Box.

4. Go to the INDEX menu to confirm that the following two entries appear:

   • TRUMA: Hx.00.nn
   • CPplus: Cy.0z.00

5. Start the inetbox2mqtt service:

   svc -u /service/inetbox2mqtt

6. Connect the LIN bus cable to the inetbox2mqtt setup and repeat the initialization process. You should now see three entries in the INDEX menu:

   • TRUMA: Hx.00.nn
   • CPplus: Cy.0z.00
   • inetbox: T23.70.0

7. Check the log by calling:

   cat /var/log/inetbox2mqtt/current | tai64nlocal

   to see output like this:

   2025-04-29 20:57:30,833 [connect] INFO: Detected cpython 3.8.18.final.0 on port: linux
   2025-04-29 20:57:30,840 [connect] INFO: MQTT Port is switched to port: 1883
   2025-04-29 20:57:30,841 [__main__] INFO: HW-Check RPi linux
   2025-04-29 20:57:30,847 [__main__] INFO: prefix: 'truma' set: 'service/truma/set/' status: 'service/truma/control_status/'
   2025-04-29 20:57:31,852 [__main__] INFO: lin-loop is running
   2025-04-29 20:57:50,879 [mqtt_async2] INFO: Connecting to ('::1', 1883, 0, 0) id=b'b827ebd304b1' clean=1
   2025-04-29 20:57:50,907 [mqtt_async2] INFO: Connecting to ('::1', 1883, 0, 0) id=b'b827ebd304b1' clean=0
   2025-04-29 20:57:50,949 [connect] INFO: MQTT connected
   

8. Access the Node-RED dashboard at https://<rpi_ip_address>:1881/dashboard (or http://<rpi_ip_address>:1880/dashboard). It should display:

   • Current Truma Combi settings
   • Room and water temperature values
   • "OK" in the System status field

The dashboard can also be accessed remotely via the Victron VRM portal under the Venus OS Large section.

MQTT Topics

The service/truma/control_status/# topics can be subscribed to. They include the current status of the CP Plus and Truma Combi systems. If your heater is off and you send a set command or use an input on the CP Plus, there is a delay of about 30 seconds before you see the first values. This behavior is normal.

Status Topics

Status Topic	Payload	Function
service/truma/control_status/#		Subscribe to all status entries
service/truma/control_status/alive	on, off	Connection status
service/truma/control_status/clock	hh:mm	CP Plus time
service/truma/control_status/current_temp_room	Temperature in °C (0, 5–30°C)	Current room temperature
service/truma/control_status/target_temp_room	Temperature in °C (0, 5–30°C)	Target room temperature
service/truma/control_status/current_temp_water	Temperature in °C (0–70°C)	Current water temperature
service/truma/control_status/target_temp_water	Temperature in °C (0–70°C)	Target water temperature
service/truma/control_status/energy_mix	gas, mix, electricity	Heater mode of operation
service/truma/control_status/el_power_level	0, 900, 1800	Max electric power consumption
service/truma/control_status/heating_mode	off, eco, high	Fan speed
service/truma/control_status/aircon_operating_mode	off, vent, cool, hot, auto	Aircon operating mode
service/truma/control_status/aircon_vent_mode	low, mid, high, night, auto	Aircon ventilator mode
service/truma/control_status/target_temp_aircon	Temperature in °C (20–32°C)	Target aircon temperature
service/truma/control_status/operating_status	0–7	Heater operation mode (0,1 = off, 7 = running)
service/truma/control_status/error_code	0–xx	Truma error codes

Set Topics

To set values, you must use the corresponding set topics. The list of set topics and valid payloads is shown below:

Set Topic	Payload	Function
service/truma/set/target_temp_room	Temperature in °C (0, 5–30°C)	Set target room temperature
service/truma/set/target_temp_water	0, 40, 60, 200	Set target water temperature (0 = off, 40 = eco, 60 = high, 200 = boost)
service/truma/set/energy_mix	gas, mix, electricity	Set mode of operation
service/truma/set/el_power_level	0, 900, 1800	Set max electric power consumption
service/truma/set/heating_mode	off, eco, high	Set fan speed (off is only accepted if room heater is off)
service/truma/set/aircon_operating_mode	off, vent, cool, hot, auto	Set aircon operating mode
service/truma/set/aircon_vent_mode	low, mid, high, night, auto	Set aircon ventilator mode
service/truma/set/target_temp_aircon	Temperature in °C (20–30°C)	Set target aircon temperature

Usage Notes

To switch on the room heating, you must set both target_temp_room > 4 and heating_mode = eco. These commands should be sent immediately after one another.

The same applies to energy_mix and el_power_level, which should be set together. Only specific combinations of these settings make sense, depending on whether the heater supports both electric and combustion modes. Valid combinations include:

• gas-0
• mix-900
• mix-1800
• electricity-900
• electricity-1800

These commands are the same for diesel and gas burners.

For the Aventa aircon, only certain combinations of aircon_operating_mode and aircon_vent_mode are valid:

• off-low
• auto-auto
• vent/cool/hot with low/mid/high

Node-RED Dashboard

The user interface is built using the Node-RED Dashboard V2 add‑on by @flowfuse.

To set up the dashboard after Node-RED is running, follow these steps:

1. Access the Node-RED editor at https://<rpi_ip_address>:1881 (or http://<rpi_ip_address>:1880), replacing <rpi_ip_address> with your Raspberry Pi’s IP address.

2. Open the menu (☰ in the top‑right corner), select Manage Palette, and install the @flowfuse/node-red-dashboard add‑on.

3. Go to Import in the menu and import the file node-red/flows.json. Alternatively copy this file to /data/home/nodered/.node-red then restart the Node-RED service:

   cp /data/inetbox2mqtt/node-red/flows.json /data/home/nodered/.node-red/
   svc -t /service/node-red-venus/

4. Select Manage Palette in te menu, click on Environment and ensure that the following environment variables have the correct values (leave default if not sure):

   • system-settings-file: Absolute path to the system settings storage file
   • fridge-gpio-pin: RPi GPIO pin for controlling the fridge D+ (ignition) signal
   • fridge-serial-device: Absolute path of the serial device for sending commands to the fridge
   • fridge-serial-baud: Serial connection baud rate

5. Open the dashboard in a browser at https://<rpi_ip_address>:1881/dashboard (or http://<rpi_ip_address>:1880/dashboard).

Note: The dashboard can also be accessed through the VRM portal under the Venus OS Large menu: https://vrm.victronenergy.com

Tip: On iOS devices, you can add the dashboard URL to your home screen. Launching it from the home screen hides Safari’s address bar and navigation buttons, making it feel like a native app.

Truma Combi Control

The Truma Combi dashboard is available under the Heating tab. It resembles the original Truma iNet System app, as shown below:

Fridge Control Dashboard

The Fridge tab provides controls for the Fridge Controller Arduino project described here: https://github.com/microfarad-de/fridge-controller

Additional Dashboards

Several other dashboards are available:

• Dashboard – Key system parameters at a glance
• Energy – Battery, solar charge controller, and propane tank information
• Environment – Data from various temperature, humidity, and air pressure sensors
• Alerts – Displays a list of active system alerts
• Settings – Advanced fridge control options, temperature offsets, and alarm thresholds