1. Four capacities that are often confused

2. Core formulas

DMX512-A packets can contain up to 513 slots including the START Code [S2], commonly leaving up to 512 data slots. Real allocation must account for fixture personality and whether a device may span a universe boundary.

3. Worked 200-metre pixel-facade case

LIKELIGHT publishes a linear-light reference with 16 controllable pixels/m [S5]. For an illustrative 200m installation using RGB at three channels per pixel:

• Pixels = 200m×16 pixels/m=3,200 pixels.
• Channels = 3,200×3=9,600 channels.
• Minimum universe count = ceiling(9,600÷512)=19 universes.
• If one four-output gateway provides four DMX universes [S4], minimum gateway count by port capacity = ceiling(19÷4)=5 gateways.
• Five four-port gateways provide 20 ports, leaving one spare output by arithmetic.

This is a capacity screen, not a released design. Actual pixel footprint, boundary handling, refresh target, controller/gateway model, cable topology and spare philosophy are 待确认.

4. Art-Net and sACN: selection is more than protocol preference

ANSI E1.31 defines lightweight streaming of DMX512 over ACN/IP and includes addressing, network management and synchronization [S1]. Artistic Licence describes Art-Net as transporting DMX512 and RDM over Ethernet; Art-Net 4 adds gateway-management features and can use sACN for live data while retaining Art-Net management [S3]. Select according to controller/gateway interoperability, discovery/management needs, multicast policy, IP plan, redundancy behavior and the client's operational skills.

5. Network-traffic screening

Do not publish an exact bandwidth number without the selected protocol version, packet size, refresh rate and universe activity. Use:

For 19 universes, 512 data slots and 30 updates/s, raw slot payload alone is 19×512×8×30=2.33 Mbit/s. This excludes Ethernet/IP/UDP/protocol overhead, synchronization, discovery, management, multicast replication and other traffic. Switch port, uplink and CPU capacity must be verified using actual packets and vendor limits.

6. Failure-domain design

Five gateways in one cabinet may simplify service but can create long DMX runs and a large common power/network failure. Distributed gateways can shorten physical branches but add outdoor enclosures, power supplies and network endpoints. Compare:

• Loss of one gateway: how many facade zones and universes go dark?
• Loss of one switch/uplink: are all gateways affected?
• Controller failure: is there approved backup or safe local playback?
• Power failure: do redundant network paths still share one supply?
• Configuration error: can a duplicate universe/source override multiple zones?

7. Seven-step release workflow

1. Freeze length, pixel density, channels per pixel and content requirement.
2. Build the channel-to-universe map without unsupported boundary splits.
3. Map each universe to a named gateway and physical port.
4. Draw switches, VLAN/IP/multicast or broadcast behavior and uplinks.
5. Calculate normal and worst-case traffic using actual device data.
6. Review failure domains, redundancy, playback/failsafe and recovery ownership.
7. Bench-test the full controller-switch-gateway-fixture chain before site deployment.

8. When not to approve the architecture

• The design says “20 universes” but has fewer than 20 documented output ports.
• Universe numbering differs among controller, gateway and commissioning files.
• Art-Net broadcast or sACN multicast is enabled without a switch/network plan.
• Redundant cables share the same switch, power supply or physical route without disclosure.
• Gateway buffering, refresh capability, synchronization and source-priority behavior are unknown.
• The largest acceptable blackout zone after a single failure is undefined.
• The product's actual channel footprint is assumed from LED count.

9. Evidence ledger

10. FAQ

Is one universe always 512 usable channels?

It commonly provides up to 512 data slots, but fixture personalities and boundary rules govern actual allocation [S2].

Can Art-Net and sACN coexist?

They can in documented architectures; avoid unintended duplicate sources or loops [S3].

Does a 1Gbps switch guarantee success?

No. Multicast/broadcast handling, packet rate, uplinks, switch CPU and configuration also matter.

Should gateways be centralized?

Not automatically. Compare physical DMX length, enclosure/power needs, maintenance access and failure domains.

How much spare capacity is enough?

There is no universal value; define spare ports, universes, switch capacity and replacement stock from project risk.

Who authored this guide?

Author: LikeLight Tom, Operations. Technical reviewer: 待确认.