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A DMX address is the first channel a light listens to. You calculate it by adding each fixture's channel count to the previous start address, so the channel blocks never overlap unless you want two lights to behave identically.
If several lights react to the same fader, or a light does not react at all, the DMX addresses are usually wrong. This guide shows how to calculate start addresses, set them by menu or DIP switch, plan them for your controller, and check them before the show.
How DMX addresses work
Universe, channels, and start address
A DMX universe carries up to 512 channels, and each channel holds a value from 0 to 255. A fixture listens to a consecutive block of those channels, starting at its address. If an RGB PAR light uses 3 channels and you set its start address to 1, it responds to channels 1–3: red, green, and blue, each from 0 (off) to 255 (full). Every other fixture on the line ignores those channels unless its own block covers them.
Footprint: how many channels a fixture uses
The number of channels a fixture occupies is its footprint. You find it in the DMX chart in the manual, and it depends on the channel mode you select. The same PAR might offer 3, 7, and 8-channel modes, and a moving head might offer a short mode and an extended mode with extra fine and effect channels. Choosing between channel modes is a tradeoff between control depth and channel budget, so lock the mode before you calculate anything.
Why each address block must be unique
When two fixtures' blocks overlap, one fader changes both lights, often in different ways: the dimmer of one light becomes the color channel of the next. The fix is always the same, recalculate so each block starts after the previous one ends. The one exception is deliberate: two identical fixtures in the same mode can share an address if you want them to do exactly the same thing, such as a pair of uplights on either side of a stage.
How to calculate start addresses
The add-and-advance method
Use three simple rules:
- Next start address = this fixture's start address + its footprint.
- Last channel used = start address + footprint − 1.
- Highest possible start address = 513 − footprint. A 14-channel fixture cannot start higher than 499, or its last channel would fall past 512.
If a fixture runs in a 12-channel mode and starts at 1, it occupies channels 1–12 and the next free start address is 13.
Example: a mixed rig
Here is the method applied to a small mixed setup: four PARs in a 7-channel mode, two moving heads in a 14-channel mode, and one fog machine that uses 2 channels.
| Fixture | Channel mode | Start address | Channels used |
|---|---|---|---|
| PAR 1 | 7CH | 1 | 1–7 |
| PAR 2 | 7CH | 8 | 8–14 |
| PAR 3 | 7CH | 15 | 15–21 |
| PAR 4 | 7CH | 22 | 22–28 |
| Moving head 1 | 14CH | 29 | 29–42 |
| Moving head 2 | 14CH | 43 | 43–56 |
| Fog machine | 2CH | 57 | 57–58 |
The next free address after this rig is 59, and the whole rig uses 58 of the 512 channels.
Physical order is not address order
The start address does not have to match the daisy-chain cable order, which helps when cable runs force a different layout. In a four-fixture setup where each light uses 6 channels, the start addresses 1, 7, 13, and 19 work whichever order the cable visits them in. What matters is the channel block math, not where the fixture sits in line.
Know the 512-channel ceiling
Your total channel count has to stay at 512 or less on a single DMX line. If the math adds up to 520, the last 8 channels have nowhere to go and you need a second universe, or a lower channel mode on some fixtures. Your controller may run out earlier than 512, as the next section shows.
Addressing for a 192-channel controller
Many compact 192-channel DMX controllers split their channels into 12 fixture buttons of 16 channels each. On those, set each fixture's start address to the first channel of its button, so each button controls one light:
| Fixture button | Start address | Channels |
|---|---|---|
| 1 | 1 | 1–16 |
| 2 | 17 | 17–32 |
| 3 | 33 | 33–48 |
| 4 | 49 | 49–64 |
| 5 | 65 | 65–80 |
| 6 | 81 | 81–96 |
| 7 | 97 | 97–112 |
| 8 | 113 | 113–128 |
| 9 | 129 | 129–144 |
| 10 | 145 | 145–160 |
| 11 | 161 | 161–176 |
| 12 | 177 | 177–192 |
A 7-channel PAR on button 2 leaves channels 24–32 unused, which is fine; the convenience of one button per light is worth the wasted channels. A fixture with a footprint over 16 spills into the next button, so pick a mode of 16 channels or fewer, or skip a button. Any fixture addressed above 192 is out of reach for this kind of controller. Check your controller's manual to confirm how it groups channels, and see choosing your first DMX controller if you are still deciding between a hardware desk and software.
Plan addresses by group and keep a patch sheet
On a software console or a larger desk, addresses are tied to fixture profiles in a patch, and the desk does the math for you. The plan still matters, because it is what you set on the lights. A few habits make the rig easier to run and to grow:
- Group by fixture type. Put all PARs together from address 1, moving heads from 101, and effects such as fog or cold spark machines from 201. Round starting numbers are easier to remember and quicker to set on DIP switches.
- Leave gaps. A gap after each group lets you add a fixture next month without readdressing the whole rig.
- Same order on the desk and on the stage. Number fixtures left to right as seen from the control position, so fixture 1 is always the one on the left.
- Check fine channels. Moving heads in extended modes add 16-bit pan and tilt channels, which change the footprint even though the fixture looks the same.
Keep a patch list in a phone note or printed sheet, and put a label with the address and mode on each fixture. A simple layout:
| Fixture | Position | Mode | Footprint | Start | End |
|---|---|---|---|---|---|
| PAR 1 | Stage left floor | 7CH | 7 | 1 | 7 |
| PAR 2 | Stage right floor | 7CH | 7 | 8 | 14 |
| Moving head 1 | Left of DJ booth | 14CH | 14 | 101 | 114 |
| Moving head 2 | Right of DJ booth | 14CH | 14 | 115 | 128 |
| Fog machine | Behind booth | 2CH | 2 | 201 | 202 |
How to set or find the address on a fixture
Fixtures with a display
Most LED fixtures show the address on an LCD or LED display. Press MENU until you see a setting such as A001 or d001, then use UP/DOWN to change it and ENTER to save. Button names vary by model, so follow the menu chart in the user manual. To find the current address of a light, open the same menu and read the number before changing anything. Also check the operating mode: a fixture left in auto, sound-active, or master/slave mode may ignore DMX entirely, even with the right address.
Fixtures with DIP switches
Older or smaller fixtures may use DIP switches instead. Each switch adds a binary value, and the address is the sum of the switches set to ON:
| Switch | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|
| Value | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 |
Common start addresses and the switches to turn ON:
| Address | Switches ON | Sum |
|---|---|---|
| 1 | 1 | 1 |
| 13 | 1, 3, 4 | 1 + 4 + 8 |
| 17 | 1, 5 | 1 + 16 |
| 33 | 1, 6 | 1 + 32 |
| 49 | 1, 5, 6 | 1 + 16 + 32 |
| 65 | 1, 7 | 1 + 64 |
| 100 | 3, 6, 7 | 4 + 32 + 64 |
| 129 | 1, 8 | 1 + 128 |
| 177 | 1, 5, 6, 8 | 1 + 16 + 32 + 128 |
| 257 | 1, 9 | 1 + 256 |
To work out any address, start from switch 9 and go down: turn a switch on if its value still fits into what is left, then subtract it. For 100, switch 7 (64) leaves 36, switch 6 (32) leaves 4, and switch 3 (4) leaves 0. Nine switches reach 511 at most. Fixtures with a tenth switch often use it for a function such as sound or slave mode rather than the address, so read the manual before you flip it. If a DIP-set light responds one channel off from where you expect, check the manual for how that model counts; a few fixtures use a different numbering.
Troubleshooting addressing problems
| Symptom | Likely cause | What to do |
|---|---|---|
| Two lights react to the same fader in different ways | Overlapping address blocks | Recalculate start addresses from the footprints |
| Two identical lights always do the same thing | Same start address | Fine if intended; otherwise give one a new block |
| Dimmer fader changes color, or pan moves tilt | Fixture mode does not match the desk or profile | Set the same mode on the fixture and in the patch |
| A light ignores everything | Fixture in auto, sound, or slave mode; address above what the controller sends | Switch to DMX mode and check the address range of the controller |
| Fader moves in software but nothing happens | Fixture not patched, or patched to the wrong address | Check the soft patch against the address on the light |
| The last lights on the line flicker or twitch | Signal problem, not addressing | Check cable type and termination |
When a fader does nothing on a computer or console, the problem is often in the patch rather than on the fixture; this guide on checking your soft patch walks through it.
Stable control assumes true DMX cable and a terminator at the end of the chain, because signal reflections can look like address mistakes. If the last light flickers or ignores commands while earlier lights behave, add a 120 Ω terminator and swap any audio XLR runs before you redo your numbering. Test each fixture on its own, one at a time from the desk, before the show.
FAQ
Can two lights share the same DMX address?
Yes, if they are the same model in the same channel mode and you want them to do exactly the same thing. Different models on the same address will clash, because their channels mean different things.
Do I need to recalculate addresses if I change a fixture's channel mode?
Yes. A new mode changes the footprint, so every fixture addressed after it may now overlap. Switching a light from a 3-channel mode to a 12-channel mode adds 9 channels to its block.
What is the highest DMX address I can use?
512 is the last channel in a universe, but a fixture's start address must leave room for its whole footprint: 513 minus the footprint. A 16-channel fixture can start no higher than 497. A 192-channel controller only reaches channel 192.
Do lights in master/slave mode need an address?
On most fixtures, no. In master/slave mode the slaves copy the master and ignore DMX addressing. Set the address when you switch the lights back to DMX control.
