What is sACN (E1.31)?
sACN, or Streaming ACN, is an Ethernet-based protocol for transporting DMX512 lighting data across IP networks.
Introduction
sACN, short for Streaming ACN, is the common name for ANSI E1.31, a standard for transporting DMX512-A lighting data over IP networks. It is widely used in architectural lighting, entertainment systems, and other applications that need to distribute lighting levels over Ethernet.
sACN carries DMX512 data without changing the meaning of the lighting channels. A console, controller, or software application can send channel levels to networked gateways and fixtures, which then output the data on a DMX512 connection.
How sACN works
An sACN sender publishes lighting data for one or more universes. A universe contains up to 512 DMX channels, and each universe is identified by a number from 1 through 63,999. Receivers subscribe to the universes they need and use the channel values to control connected equipment.
sACN supports both multicast and unicast delivery:
- Multicast: One sender can distribute a universe to multiple receivers subscribed to that multicast group.
- Unicast: A sender can transmit a universe directly to one or more specified receiver addresses.
Multicast can simplify distribution in a system with many receivers, while unicast can help limit network traffic when only a small number of devices need a universe. Network switches should be configured appropriately for the chosen delivery method.
Priority and synchronization
Each sACN data stream includes a priority value. When multiple sources send the same universe, a receiver can use the highest-priority source and fall back to another source when the higher-priority stream is no longer available. This is useful for backup consoles and redundant lighting controllers.
sACN also provides synchronization mechanisms for coordinated updates across multiple universes. A controller can prepare changes in several universes and release them together, reducing visible timing differences during complex lighting scenes.
sACN and DMX512
DMX512 is commonly used as the device-level lighting interface, while sACN is used to carry that data over an Ethernet network. An sACN-to-DMX gateway converts network universes into one or more physical DMX512 outputs. The gateway configuration must match the universe numbers, channel offsets, and output assignments used by the lighting controller.
sACN does not replace the need to document fixture addresses, channel functions, DMX modes, and network topology. Clear universe and channel mapping is essential when integrating equipment from different manufacturers.
sACN in building and architectural lighting
sACN is useful when lighting systems span multiple rooms, floors, or buildings and need a network-based distribution method. It can coexist with other building automation protocols on a managed IP network, but lighting traffic, multicast behavior, and network security should be reviewed during system design.
For reliable operation, document the universe plan, multicast or unicast assignments, priority behavior, switch configuration, and the fallback state used when a controller or network connection fails.