QSC Q-SYS · KNXnet/IP · DPT 18.001 · Preset Recall · Volume Control · 10 min read

QSC Q-SYS KNX Plugin: Conference Room Preset Recall and KNX Volume Control

QSC Q-SYS integrates natively with KNX via an official plugin available in Q-SYS Designer. The plugin creates a KNXnet/IP tunnelling connection directly from the Q-SYS Core processor, exposing Q-SYS controls as KNX group address objects — enabling the KNX building automation system to trigger AV presets, adjust volume and receive DSP status feedback without any additional middleware.

Q-SYS Designer Plugin Manager installation

The Q-SYS KNX plugin is distributed through the Q-SYS Plugin Manager, accessible directly within Q-SYS Designer. The plugin installs as a component that can be placed in any Q-SYS design file, creating the KNXnet/IP client connection.

Plugin installation steps

1. Open Q-SYS Designer → Tools → Plugin Manager
   Search: "KNX"
   → Install: "KNX (KNXnet/IP Tunneling)" by QSC
   Version: 1.3.x or later (verify at qsc.com/plugins)

2. Add plugin to design:
   Component Library → Plugins → KNX (KNXnet/IP Tunneling)
   Drag to design canvas

3. Plugin properties panel:
   Name: KNX-Gateway-CR1 (conference room 1)
   IP Address: <KNX IP router address> (e.g. 192.168.1.100)
   Port: 3671 (KNXnet/IP standard)
   Physical Address: 1.1.200 (assign unique PA per Q-SYS Core)
   Connection timeout: 5000 ms
   Heartbeat interval: 10000 ms

4. Verify connection:
   Deploy design to Q-SYS Core
   Plugin status LED → GREEN = connected to KNX IP router
   ETS6 → Diagnostic → Individual Address → scan bus
   → Q-SYS PA 1.1.200 should appear as active device

Control binding to KNX group addresses

Each Q-SYS control pin exposed in the plugin can be bound to a KNX group address with a specific DPT. The binding is configured directly in the Q-SYS plugin component properties, associating Q-SYS faders, buttons and level meters with KNX GAs.

Q-SYS controlKNX DPTGroup addressDirection
Level fader (0–100%)DPT 5.001 (1-byte, 0–100%)7/0/0 — CR1 VolumeKNX → Q-SYS + Q-SYS → KNX (bidirectional)
Mute buttonDPT 1.001 (1-bit)7/0/1 — CR1 MuteBidirectional
Preset recallDPT 18.001 (1-byte scene)7/0/2 — CR1 PresetKNX → Q-SYS
Output level (meter)DPT 5.001 (1-byte)7/0/3 — CR1 Output LevelQ-SYS → KNX (status)
Input selectorDPT 5.010 (1-byte unsigned)7/0/4 — CR1 Input SelectKNX → Q-SYS

DPT 18.001 preset recall encoding

DPT 18.001 (1-byte scene):
  Bit 7 (MSB): 0 = activate scene, 1 = learn scene
  Bits 0–5: scene number (0–63)

Scene recall values (activate, bit 7 = 0):
  Value 0  = Scene 1 (Standby / AV off)
  Value 1  = Scene 2 (Presentation — laptop input)
  Value 2  = Scene 3 (Video conference — camera input)
  Value 3  = Scene 4 (Audio only — microphone + playback)

Example: KNX Group Monitor write value 2 to GA 7/0/2
  → Q-SYS preset 3 recalled (Video conference mode)
  → DSP routing: camera mic input → loudspeakers + codec
  → Gain structure: optimised for video conference
  → All in one KNX telegram

Bidirectional status feedback

The Q-SYS KNX plugin supports bidirectional communication — Q-SYS can both receive commands from KNX GAs and publish status back to KNX GAs. This allows the KNX touchpanel to display the current volume level and mute state as read from the DSP, rather than as a locally maintained display value.

KNX → Q-SYS (command)

  • KNX touchpanel writes volume (0–100%) to GA 7/0/0
  • Plugin receives DPT 5.001 value → scales to Q-SYS fader
  • Q-SYS fader moves → DSP gain adjusts in real time
  • KNX mute button → GA 7/0/1 = 1 → Q-SYS mute ON

Q-SYS → KNX (status)

  • Q-SYS fader moved from UCI touchpanel → GA 7/0/0 updated
  • KNX Gira touchpanel reflects current volume correctly
  • Mute state changes → GA 7/0/1 updated → KNX button LED
  • Send on change: 1% threshold to avoid telegram flooding

Conference room automation scenario

The complete conference room AV automation scenario triggers from a KNX occupancy sensor, recalling the appropriate Q-SYS preset and simultaneously adjusting DALI lighting to the meeting scene — all from a single KNX occupancy event.

Occupancy-triggered AV scene (KNX logic module)

Trigger: GA 5/1/10 (CR1 Occupancy sensor) = 1

Actions (parallel, via logic module):
  1. Q-SYS preset recall:
     → Write value 2 (Scene 3 = Video conference) to GA 7/0/2
     → Q-SYS: activate routing preset, unmute microphones,
               set loudspeaker volume to 50% (value 128 on GA 7/0/0)

  2. DALI lighting scene:
     → Write scene 3 (Meeting) to DALI GA 3/1/0
     → Luminaires: 60% level, 4000K, perimeter dim to 30%

  3. Display power on:
     → Write 1 to GA 7/1/0 (display power)
     → KNX binary output relay → display RS-232/CEC power on

  4. HDMI routing (optional):
     → Write 1 to GA 7/1/1 (default input = laptop USB-C)

On vacancy (GA 5/1/10 = 0):
  After 15-minute no-occupancy delay:
  → Write 0 to GA 7/0/2 (Q-SYS recall Scene 1 = Standby)
  → Q-SYS: mute all inputs, reduce volume to 0
  → Write scene 0 to DALI GA 3/1/0 (lights off)
  → Write 0 to GA 7/1/0 (display power off)

UCI touchpanel integration

Q-SYS UCI (User Control Interface) touchpanels can coexist with KNX control — the UCI panel controls Q-SYS directly via the Q-SYS Core network, while KNX provides room-level automation. The bidirectional plugin binding ensures both control surfaces remain synchronised.

UCI vs KNX priority: if both a UCI touchpanel and a KNX scene recall attempt to set volume simultaneously (a rare race condition), Q-SYS processes the most recently received command. There is no priority mechanism — ensure KNX automation scenes only fire on occupancy events or explicit user actions from KNX touchpanels, not on continuous polling.

Commissioning test

Verify the complete Q-SYS–KNX chain using ETS6 Group Monitor and Q-SYS Designer real-time control view simultaneously. The test confirms both command and feedback directions work correctly before handover to the client.

Commissioning test sequence

1. KNX → Q-SYS volume test:
   ETS6 Group Monitor → write 128 (50%) to GA 7/0/0 (DPT 5.001)
   → Q-SYS Designer control view: fader at 50%
   → Audio signal at loudspeaker: -6 dBFS headroom (verify with meter)

2. Q-SYS → KNX feedback test:
   Q-SYS Designer: drag level fader to 75%
   → ETS6 Group Monitor: GA 7/0/0 should update to 191 (75% = 191/255)
   → Gira KNX touchpanel (if installed): volume slider moves to 75%

3. Mute test:
   Write 1 to GA 7/0/1 → Q-SYS mute ON → no audio at speaker
   Write 0 to GA 7/0/1 → Q-SYS mute OFF → audio resumes

4. Preset recall test:
   Write 0 to GA 7/0/2 → Q-SYS Scene 1 (Standby) → gain structure flat
   Write 1 to GA 7/0/2 → Q-SYS Scene 2 (Presentation) → verify routing
   Write 2 to GA 7/0/2 → Q-SYS Scene 3 (Video conf.) → verify codec routing

5. Occupancy trigger test:
   Write 1 to GA 5/1/10 → confirm all parallel actions fire:
     Q-SYS preset 3 recalled, DALI scene set, display powers on
   Write 0 to GA 5/1/10 → after 15-min timer: confirm AV off sequence

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