Introduction and Terminology
Art-Net is an ethernet protocol based on the TCP/IP protocol suite. Its purpose is to allow transfer of large amounts of DMX512 data over a wide area using standard networking technology. It does this by allocating each universe a Port-Address. A DMX-to-Art-Net product puts DMX data on the network with a specific Port-Address. Conversely, an Art-Net-to-DMX product collects any universe with its Port-Address and outputs it as DMX512.
Art-Net contains a number of packet definitions that allow data to be efficiently encapsulated inside a UDP packet. These UDP packets are then transferred across the network. Each of the packet names is prefixed with “Art”, for example ArtDmx and ArtRdm. While there are around 20 packet definitions in Art-Net, only three are critical to its operation. These are ArtPoll, ArtPollReply and ArtDmx.
The protocol defines a Controller which is optimised for generating control data. It also defines a Node, which is optimised for converting to and from Art-Net data. A Node can support over 1000 logical inputs and 1000 logical outputs; these are referred to as Input-Ports and Output-Ports. Products report their quantity of ports using multiple ArtPollReply packets.
Glossary of Art-Net Terms
- ArtPoll: An Art-Net packet used to discover the existence of Art-Net nodes.
- ArtPollReply: An Art-Net packet sent by a Node in response to receipt of an ArtPoll.
- ArtDmx: The Art-Net packet used to transfer zero start code DMX512 packets over the network.
- Controller: A generic term describing an Art-Net device with the primary task of generating control data. For example, a lighting console.
- Discovery: The process by which a controller discovers which nodes want to receive which universes of DMX512 data.
- Download: Art-Net specifies the direction of file transfer to be from a node to a controller during a download. That is, a controller would download a copy of a node’s configuration file in order to retrieve a local copy.
- Kiloverse: A group of 1024 Universes.
- Media Server: A generic term describing an Art-Net device capable of generating control data based on the ‘mx’ Media Extensions to Art-Net.
- Net: A group of 16 consecutive Sub-Nets or 256 consecutive Universes is referred to as a net. There are 128 Nets in total.
- Node: A device that is primarily designed to convert DMX512 to or from Art-Net. A Node supports up to 4 Input-Ports and 4 Output-Ports.
- OpCode: The 16-bit number which defines the packet type in Art-Net
- Port-Address: one of the 32,768 possible addresses to which a DMX frame can be directed. The Port-Address is a 15-bit number composed of Net+Sub-Net+Universe.
- Sub-Net: A group of 16 consecutive universes is referred to as a sub-net (not to be confused with the subnet mask).
- Subscription: The term used to describe a Node that is consuming a particular universe of DMX512 data
- Universe: A single DMX512 frame of 512 channels.
- Upload: Art-Net specifies the direction of file transfer to be from a controller to a node during an upload. That is, a controller would upload new firmware to a node.