A connection is the bridge between ARC and a protocol or piece of gear. It’s the layer that lets ARC speak MQTT, Z-Wave, DMX, Hue, and the rest. You set up a connection once at System → Connections, and every device that uses that protocol rides on top of it — whether that device is location-wide or lives inside one game.
Why connections live in System
Connections are business-wide on purpose. A single MQTT broker, one Hue bridge, or one Z-Wave controller usually serves your whole location, so ARC keeps them in one shared place rather than buried in a single game. Add a connection here, and both System devices and a game’s in-room devices can use it.
Why connections come first
ARC can’t reach a device until it knows how to talk to it. The connection holds that “how” — the broker address, the controller, the bridge, the USB stick. So the workflow is always the same:
- Add the connection (the protocol bridge) at System → Connections.
- Add the devices that use it — in System for location-wide gear, or in a game’s Editor for props.
If you try to add a device before its connection exists, ARC has nothing to attach it to. Adding the connection first is the prerequisite for everything else in the devices area.
One connection, many devices
You usually need only a handful of connections for a whole location. A single MQTT connection can carry dozens of devices; one Hue connection covers every light on that bridge. Add the bridge once, then add devices freely.
Connection types
You manage connections at System → Connections. When you add one, ARC shows a picker of the connection types below. Pick the one that matches your hardware.
| Connection | What it’s for |
|---|---|
| MQTT | The most flexible option. Connects ARC to an MQTT broker — ARC’s built-in broker or an external one — so any device that publishes or subscribes over MQTT can talk to ARC. A great default for custom props and ESP-based gear. |
| PLC (Modbus) | Talks to industrial controllers over Modbus TCP. Use this when your room is wired through a PLC and you want ARC to read or set coils and registers. |
| DMX | Drives stage and architectural lighting fixtures over Art-Net or sACN. Use this for DMX light rigs, fog machines, and other DMX-controlled effects. |
| OSC | Sends and receives Open Sound Control messages. Common for bridging to audio, video, and show-control software that speaks OSC. |
| QLC+ | Runs lighting looks you’ve built in the QLC+ lighting app. Use this when your lighting design already lives in QLC+ and you want ARC to fire those looks. |
| Bluetooth Gateway | Brings Bluetooth Low Energy (BLE) sensors into ARC through a gateway — a Shelly BLU USB gateway or an ESP32. Use this for Shelly BLU buttons, motion, and door sensors. |
| Node-RED | A WebSocket bridge that connects ARC to a Node-RED flow. Use this when you already build logic in Node-RED and want it to exchange signals with ARC. |
| Z-Wave | Connects a Z-Wave controller (USB stick or networked) so ARC can use Z-Wave locks, sensors, switches, and dimmers. |
| Zigbee | Connects a native Zigbee coordinator so ARC can use paired Zigbee devices — buttons, sensors, plugs, and lights. |
| Hue | Links a Philips Hue bridge over your local network. Use this to control Hue lights, scenes, and groups from ARC. |
| Raspberry Pi | A multi-role bridge: a single Pi can drive a room display, handle GPIO inputs and outputs, and act as a Bluetooth gateway. See Raspberry Pi and Windows Bridge. |
| Windows Bridge | Turns a Windows PC into a fullscreen display kiosk for a room screen. Also covered in Raspberry Pi and Windows Bridge. |
Not sure which to pick?
If your prop is custom and you have any choice in the matter, MQTT is the most flexible and best-supported path. For off-the-shelf smart gear, match the connection to the radio the device already uses (Z-Wave, Zigbee, or Hue).
Adding a connection
The exact fields differ per connection type — an MQTT connection asks for a broker address, a Z-Wave connection asks for a controller — but the general flow is the same.
- Go to System → Connections.
- Click to add a connection and choose the type that matches your hardware from the picker.
- Fill in the connection details ARC asks for, such as a broker address, controller, or bridge.
- Save the connection. ARC attempts to reach the bridge and shows its status.
- Confirm the connection comes up healthy before you start adding devices to it.
Some connections — Raspberry Pi and Windows Bridge — don’t need you to enter an address at all. They announce themselves on your local network and appear in the Connections list automatically once you install the bridge software. Those are covered in Raspberry Pi and Windows Bridge.
Keep it on the local network
ARC is local-first, so a connection bridges ARC to gear on your own LAN. Make sure the broker, controller, or bridge sits on the same dependable local network as the ARC host — game-critical signals shouldn’t depend on the internet.
Next step
With a connection in place, you’re ready to add the devices that use it.
- For location-wide gear like lobby lights and signs, see System devices.
- For props inside a specific room, see game devices.
- For displays, GPIO, and Bluetooth field hardware, see Raspberry Pi and Windows Bridge.