DMX Basics

An introduction to DMX512 for lighting control.

What is DMX?

DMX512 (Digital Multiplex 512) is the standard protocol for controlling stage lighting. Developed in 1986, it's used worldwide for theatrical, concert, and architectural lighting.

Key Concepts

Channels

• A DMX universe has 512 channels
• Each channel sends a value from 0 to 255
• Channels control specific functions (dimmer, color, position)

Fixtures

Each fixture uses one or more channels:

• Simple dimmer: 1 channel
• RGB LED: 3 channels (Red, Green, Blue)
• Moving head: 8-40+ channels

Addressing

Fixtures are assigned a start address (1-512):

• A fixture at address 1 with 4 channels uses channels 1-4
• The next fixture could start at address 5

No overlapping: Each channel should belong to only one fixture.

Universes

One Universe = 512 Channels

For larger shows:

• Universe 1: Channels 1-512
• Universe 2: Channels 513-1024 (conceptually)
• Each universe is independent

Multiple Universes

Connect multiple universes via:

• Multiple DMX cables
• Art-Net over Ethernet (unlimited universes)
• sACN (Streaming ACN)

Channel Values

The 0-255 Range

Common Uses

Fixture Modes

Many fixtures have multiple DMX modes:

Example: LED Par

3-Channel Mode

• Ch 1: Red
• Ch 2: Green
• Ch 3: Blue

7-Channel Mode

• Ch 1: Dimmer
• Ch 2: Red
• Ch 3: Green
• Ch 4: Blue
• Ch 5: Strobe
• Ch 6: Color macros
• Ch 7: Mode select

The fixture's physical setting must match the mode in your software.

Address Planning

Simple Example

Best Practices

1. Leave gaps for future expansion
2. Group similar fixtures together
3. Document everything
4. Use round numbers (1, 10, 20, 50, 100...)

Physical Connections

DMX Cables

• 5-pin XLR (professional standard)
• 3-pin XLR (common but not to spec)
• Never use audio cables for DMX

Daisy Chain

Connect fixtures in series:

Controller → Fixture 1 → Fixture 2 → Fixture 3 → Terminator

Termination

Add a 120Ω terminator at the end of long runs to prevent signal reflection.

Cable Limits

• Maximum 300m (1000ft) per run
• Maximum 32 devices per run
• Use splitters for longer/larger installations

Art-Net

For Ethernet-based DMX:

Advantages

• Multiple universes over one cable
• Longer distances (100m per segment)
• Network infrastructure compatibility

Addressing

Art-Net uses Net/Subnet/Universe:

• Net: 0-127
• Subnet: 0-15
• Universe: 0-15

Simple setup: Net 0, Subnet 0, Universe 0, 1, 2...

Troubleshooting

No Output

1. Check cable connections
2. Verify fixture is in DMX mode
3. Confirm address matches
4. Check for address conflicts

Flickering

1. Check for cable damage
2. Add/verify termination
3. Reduce cable length
4. Check for electrical interference

Wrong Behavior

1. Verify fixture mode matches patch
2. Check channel assignments
3. Confirm value ranges

Related

• DMX Patching
• Art-Net Setup
• Address Space Panel