DMX Channel Charts and Fixture Profiles: How to Read a Manual
After you address a fixture, does channel 1 change colour or swing the head? The answer is in the fixture’s channel chart. Learning to read that table removes the hours otherwise spent at the console asking why nothing is happening.
In short
- A channel chart lists each channel’s function and what its value ranges mean.
- Colour and dimmer are continuous; shutter and gobo are discrete.
- Every mode has a different chart — console and fixture must agree.
- Mode mismatch is the number-one cause of inexplicable colour and dimmer faults.
- A fixture profile teaches the chart to the console; GDTF is vendor neutral.
- Keep a patch sheet with address, mode and channel count after installation.
What a channel chart is
A channel chart (DMX chart) lists what each of a fixture’s channels does and what each value means. It appears in every manual and is specific to that device — two models from the same manufacturer can be completely different.
A typical chart for a simple RGBW par:
| Channel | Function | Value range | Meaning |
|---|---|---|---|
| 1 | Master dimmer | 0–255 | Off → full |
| 2 | Red | 0–255 | None → full |
| 3 | Green | 0–255 | None → full |
| 4 | Blue | 0–255 | None → full |
| 5 | White | 0–255 | None → full |
| 6 | Shutter / strobe | 0–7 8–250 251–255 | Closed Strobe, slow to fast Open |
Continuous versus discrete channels
This is the distinction that matters most. Colour and dimmer channels are continuous: they change progressively from 0 to 255. Shutter, gobo, prism and macro channels are discrete: bands of values select different functions.
On a discrete channel, parking the value “somewhere in the middle” achieves nothing useful. Set channel 6 to 5 and the light stays closed; set it to 128 and it strobes. Touching these channels without reading the range table is the classic source of unwanted flashes during a show.
Modes: same fixture, different chart
Most fixtures offer several modes in their menu, and every mode has a different chart. The par above, in 4-channel basic mode:
| Channel | Basic mode (4 ch) | Standard mode (6 ch) |
|---|---|---|
| 1 | Red | Master dimmer |
| 2 | Green | Red |
| 3 | Blue | Green |
| 4 | White | Blue |
| 5 | — | White |
| 6 | — | Shutter / strobe |
The single most common mistake
Patching the fixture in standard mode on the console while the fixture’s menu is still on basic. Every channel shifts by one: the console sends “dimmer” and the fixture reads it as “red”. The result is colours with no logical explanation and a dimmer that does nothing. When a fixture behaves oddly, check the mode match first.
Fixture profiles (personalities)
You do not have to build every fixture channel by channel. A fixture profile is a definition file describing the chart in a form the console understands. Load the profile, give it a start address, and the console maps the channels for you and presents meaningful controls: colour, pan, gobo.
Where profiles come from:
- The console’s own library — thousands of fixtures ship built in.
- The manufacturer’s website — profiles for newer models.
- GDTF (General Device Type Format) — an open, vendor-neutral standard, increasingly common, where one file works across different consoles.
- A profile you write yourself — built by hand in the console’s profile editor for devices with no published profile.
Reading a manual carefully
- Confirm the manual matches your hardware revision; manufacturers revise quietly.
- Check whether channels are numbered from 1 or from 0. Some manuals say “channel 0” and the whole chart shifts.
- If there are 16-bit channels, note the coarse/fine order.
- Write down “safe” defaults for discrete channels (for instance the open range on shutter).
- When you change mode, re-address every fixture that follows.
Keep your own patch sheet
A simple table after installation makes future maintenance far easier: fixture name, physical position, model, mode, channel count and start address. When you have to swap a fixture six months later, that sheet saves you from re-addressing the whole line.
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