2025-04-14

Streaming Architecture for Control Networks

author: Shally

Streaming Architecture for Control Networks

Streaming Architecture for Control Networks (sACN) is an Ethernet light control protocol standardized by ANSI E1.31, designed for high reliability and large-scale DMX512 data transmission. Here is a full breakdown of its technical details, data structure and application scenarios:

One. sACN core features

1. Basis of agreement

Based on UDP/IP: port 5568, Unicast and Multicast are supported.
DMX over IP: Each sACN data stream (Universe) carries 512 DMX channels, but the protocol itself supports unlimited scaling.
Priority mechanism: The data stream can be set to 0-200 levels of priority, and the high priority can preempt the low priority signal (critical performance protection).
Standardization: Developed by ESTA (Entertainment Services and Technology Association), compatible with RDM (via ANSI E1.33).

2. Key differences with Art-Net

peculiarity	sACN (E1.31)	Art-Net
standardization	ANSI Official Standard (E1.31)	Private protocol (but open documentation)
priority	Supports 0-200 level preemption	There is no priority mechanism
Multicast management	Automatically Assign multicast groups (239.255.x.x)	You need to manually configure the multicast address
Redundant design	Dual-network hot backup (E1.31-2018)	Third-party implementation
Typical delay	2-10ms (Gigabit network)	2-10ms

Two.sACN protocol architecture

1. Packet structure

sACN packets are divided into three layers:
At the UDP/IP layer, the destination port is 5568. IPv4 and IPv6 are supported.
ACN Root Layer: Contains the protocol ID and UUID.
Framing Layer & DMP Layer: Encapsulate DMX data.

Key field parsing

// ACN Root Layer (112 bytes)
0-3: "ACN" Packet Identifier (0x41434E00)
16-31: UUID (Fixed value 0x6382536A... , identify the sACN protocol)
48-51: Length of Framing Layer (high byte first)
// Framing Layer (77 bytes)
0: Flags (priority, serial number, etc.)
1: Priority (0-200)
2: Sequence Number (packet loss prevention)
3-4: Universe (1-63999)
9-40: Source Name (UTF-8 string, such as "LightingConsole-1")
// DMP Layer (523 bytes)
0: Flags
1: Start code (usually 0x00)
2: Address Type & Data Type (fixed value 0xA1)
3-4: First Property Address (high byte before, fixed 0x0000)
5-6: Address Increment (fixed 0x0001)
7-518: DMX512 data (512 bytes)

2. Multicast and unicast

Multicast address:

Automatically calculated as 239.255..

For example, Universe 1 → 239.255.0.1

Unicast: sends the IP address directly to the target device, suitable for point-to-point control.

Three.sACN Advanced functions

1. Priority & Preemption

Priority value: 0 (lowest) to 200 (highest), default 100.
Preemption rules:
A high priority data stream interrupts a low priority stream.
If the Precedence is the same, the latest packet overwrites the Last Takes Precedence.

2. Synchronization mechanism

sACN Sync: Dedicated synchronization package (Universe 0) to ensure that multiple devices execute DMX instructions simultaneously.
Application scenario: frame-level synchronization of LED wall and light show (error <1ms).

3. Redundant design (added in E1.31-2018)

Dual-network hot backup: The device monitors two network interfaces at the same time and automatically switches to the backup network when the primary network fails.
Data consistency check: Use Sequence Number to prevent data inconsistency.

Four. Application scenarios of sACN

1. Large-scale performance system

Radio and Television evening:
The main console (GrandMA3) sends high priority signals through sACN, and the backup console (Hog4) is set to low priority.
Music Festival Main stage:
Multiple light controllers synchronize output, ensuring that all lamps change synchronously through the Sync package.

2. Building lighting

Super High rise Media facade:
Control tens of thousands of LED pixels with sACN multicast and eliminate latency in combination with PTPv2 (Precision Time Protocol).

3. Combination with RDM

The ANSI E1.33 standard allows RDM instructions to be transmitted via sACN, enabling:
Remote reading lamp temperature, voltage.
Change DMX addresses in batches without manual DIP switches.

Five.sACN Practice Guide

1. Network configuration requirements

Switch Settings:
Enable IGMP Snooping (to avoid multicast storms).
Disable QoS (unless priority scheduling is explicitly required).
IP planning:
Controller: 10.0.0.1/24
Device nodes: 10.0.0.2 to 254/24

2. Troubleshooting tool

Wireshark filtering:
udp.port == 5568 && data[0:4] == 0x41434E00
Common problems:
Data loss: Check whether the Sequence Number is continuous.
Sync delay: Check the sync packet sending frequency (usually 30Hz).

3. Performance optimization

Gigabit network: Single port support >40,000 DMX channels/second.
VLAN isolation: Separating sACN traffic from other systems, such as audio Dante

Six.sACN vs Art-Net How to choose?

Map	Recommendation protocol	argument
Broadcast television/High reliability production	sACN	Priority preemption and standardization support
Small and medium-sized performance	Art-Net	Wider device compatibility
LED pixel control	sACN + Sync	Higher synchronization accuracy
Architectural lighting	sACN or DALI	It must be based on the system scale

Seven.Future evolution

sACN 2.0 (Draft) :

Supports higher channel density (single packet >512 channels).
Deep PTPv2 integration (nanosecond synchronization).

Combined with NMOS:

IS-04/IS-05 enables automatic device discovery and API control.

For more knowledge about LED industry, please pay attention to our LIKELIGHT.If you are not sure which LED fixture is best for your project or need help with layout configuration, contact us LIKLEIGHT, we are a professional manufacturer of LED lamps in China;we have engineers and 24 hours customer service for you.Phone:+86-755-23328395, Email :contact@like-light.com,Wechat/WhatsApp:86-132-66666-320.