Two-Way Sync a KNX Slider with a B&O Mozart Product's Volume

Introduction

Integrate your KNX control system with your high-end Bang & Olufsen Mozart audio products for a unified smart home experience. This tutorial will walk you through setting up two BeoLiving Intelligence macros to create a robust, two-way binding between a KNX slider and a Mozart product’s volume. You’ll be able to adjust the volume from your KNX wall panel, and the slider will accurately reflect any volume changes made via a remote control or the BeoLiving app, keeping everything perfectly in sync.

Prerequisites

Before you begin, ensure you have a KNX “1 byte unsigned integer (DPT 5.001)” resource configured in your BeoLiving Intelligence that corresponds to your KNX slider. This resource will represent the volume level (0-255) on the KNX bus.

How to Set It Up

Creating a two-way synchronization requires two separate macros. One macro will listen for changes from the KNX slider and update the Mozart product’s volume. The second macro will do the reverse: listen for volume changes on the Mozart product and update the KNX slider.

Part 1: Macro from KNX Slider to Mozart Volume

Navigate to the Macro tab and create a new Macro. Name it something descriptive, like “KNX to Mozart Volume”.
As the event, add the STATE_UPDATE event from your KNX slider resource. It will look like: RndLab/LivingRoom/_KNX_GROUP_ADDRESS/knxSlider/STATE_UPDATE.
Press the “Convert to code” button in the commands table.
Copy the Lua code from the Macro 1 section below and paste it into the code text area.
Customize the targetProduct variable in the SETTINGS section to match your Mozart device address.
Save the macro.

Part 2: Macro from Mozart Volume to KNX Slider

Create another new Macro. Name it something descriptive, like “Mozart to KNX Volume”.
As the event, add the STATE_UPDATE event from your Mozart RENDERER product. It will look like: RndLab/LivingRoom/RENDERER/Beovision Theatre-35554298/STATE_UPDATE.
Press the “Convert to code” button.
Copy the Lua code from the Macro 2 section below and paste it into the code text area.
Customize the knxSlider and macroAddress variables in the SETTINGS section. The macroAddress must be the full address of this macro itself.
Save the macro.

Now, when you adjust the KNX slider, the B&O product’s volume should change. When you change the volume using a Beoremote or the B&O App, the KNX slider should update its position after a short delay.

The Lua Code

Macro 1: KNX Slider → Mozart Product

This macro scales the KNX value (0-255) to the Mozart volume range (0-90) and updates the product, preventing command loops by checking the current volume first.

-- === KNX SLIDER TO MOZART VOLUME ===
-- This macro listens for changes on a KNX slider and updates the volume
-- of a target Mozart product. It includes volume scaling from KNX's 0-255
-- range to the Mozart's 0-90 range.
--
-- How to use it:
--  1. Create a Macro triggered by the STATE_UPDATE of your
--     KNX "1 byte unsigned integer" resource.
--     e.g., RndLab/LivingRoom/_KNX_GROUP_ADDRESS/knxSlider/STATE_UPDATE
--  2. Press "Convert to code" and paste this code.
--  3. Update the SETTINGS section with your device address.
-- =======================================================================

function(event, engine)
  -- --------------------------------------------------------
  -- SETTINGS
  -- --------------------------------------------------------
  -- Replace this with the address of the target Mozart product:
  local targetProduct = "RndLab/LivingRoom/RENDERER/Beovision Theatre-35554298"
  -- --------------------------------------------------------
  -- DO NOT EDIT BELOW HERE UNLESS YOU UNDERSTAND THE CODE!
  -- --------------------------------------------------------

  -- Check if the VALUE parameter of the KNX resource was updated
  if event.updated("VALUE") then
    -- Get the raw value (0-255) from the KNX slider
    local knxValue = event.get_number("VALUE")
    
    -- Scale the KNX value (0-255) to the B&O volume range (0-90)
    local targetVolume = math.floor((knxValue / 255) * 90)

    -- Query the current state of the target product to get its volume
    local productState = engine.query(targetProduct)
    if productState and productState[1] then
        local currentVolume = productState[1].get_number("VOLUME")

        -- To prevent loops, only send the command if the new volume is different
        if currentVolume ~= targetVolume then
            Debug("KNX->Mozart: Setting volume from " .. tostring(currentVolume) .. " to " .. tostring(targetVolume))
            engine.fire(targetProduct .. "/SET_VOLUME?VOLUME=" .. targetVolume)
        else
            Debug("KNX->Mozart: Volume already at " .. tostring(targetVolume) .. ". Ignoring.")
        end
    end
  end
end

Once added it should look like:

Macro 1

Macro 2: Mozart Product → KNX Slider (with Debounce)

This macro listens for volume changes on the Mozart product, debounces the events to avoid flooding the KNX bus, scales the volume (0-90) to the KNX range (0-255), and updates the slider.

-- === MOZART VOLUME TO KNX SLIDER (WITH DEBOUNCE) ===
-- This macro listens for volume changes on a Mozart product and updates
-- a KNX slider. It includes a debounce mechanism to prevent flooding the
-- KNX bus with rapid volume changes.
--
-- How to use it:
--  1. Create a Macro triggered by the STATE_UPDATE of your Mozart RENDERER.
--     e.g., RndLab/LivingRoom/RENDERER/Beovision Theatre-35554298/STATE_UPDATE
--  2. Press "Convert to code" and paste this code.
--  3. Update the SETTINGS section with your device and macro addresses.
-- =======================================================================

function(event, engine)
  -- --------------------------------------------------------
  -- SETTINGS
  -- --------------------------------------------------------
  -- Replace this with the address of the KNX slider resource ("1 byte unsigned integer"):
  local knxSlider = "RndLab/LivingRoom/_KNX_GROUP_ADDRESS/knxSlider"
  -- Replace this with the address of this macro, required for the debouncer.
  -- Find it in the BeoLiving Intelligence UI (e.g., Main/global/MACRO/Mozart to KNX Volume).
  local macroAddress = "Main/global/MACRO/Mozart to KNX Volume"
  -- Debounce delay in milliseconds to prevent flooding the KNX bus.
  local debounce_ms = 500
  -- --------------------------------------------------------
  -- DO NOT EDIT BELOW HERE UNLESS YOU UNDERSTAND THE CODE!
  -- --------------------------------------------------------
  
  -- Check if the VOLUME parameter of the Mozart product was updated
  if event.updated("VOLUME") then
    -- 1. Debounce: Cancel any other instance of this macro that is waiting.
    engine.fire(macroAddress .. "/CANCEL OTHER")
    -- Wait for a short period to see if more volume changes come in.
    engine.delay(0, debounce_ms)

    -- Get the new volume (0-90) from the Mozart product.
    -- We re-query the state in case it changed during the delay.
    local productState = engine.query(event.area() .. "/" .. event.zone() .. "/" .. event.type() .. "/" .. event.name())
    local mozartVolume = productState[1].get_number("VOLUME")

    -- Scale the B&O volume (0-90) to the KNX slider range (0-255)
    local targetKnxValue = math.floor((mozartVolume / 90) * 255)

    -- Query the current state of the KNX slider
    local knxState = engine.query(knxSlider)
    if knxState and knxState[1] then
        local currentKnxValue = knxState[1].get_number("VALUE")

        -- To prevent loops, only send the command if the new value is different
        if currentKnxValue ~= targetKnxValue then
            Debug("Mozart->KNX: Setting slider from " .. tostring(currentKnxValue) .. " to " .. tostring(targetKnxValue))
            engine.fire(knxSlider .. "/SET?VALUE=" .. targetKnxValue)
        else
            Debug("Mozart->KNX: Slider value already at " .. tostring(targetKnxValue) .. ". Ignoring.")
        end
    end
  end
end

A Note on Volume Scaling

Bang & Olufsen Mozart products typically use a volume scale of 0 to 90. In contrast, a KNX “1 byte unsigned integer” (DPT 5.001) has a range of 0 to 255. The provided macros automatically handle the mathematical conversion between these two scales. This ensures that when your B&O volume is at its maximum (90), the KNX slider correctly shows its maximum value (255), and vice-versa, with proportional mapping for all values in between.