Finding the channels used by your fixture

[SimpleDMX]

Finding the channels used by your fixture

Before you can control a moving head or other DMX fixture from SDC, you need to know which DMX channel controls each function - pan, tilt, dimmer, colors, gobos, and so on. This information is always found in the fixture's user manual, usually in a "DMX channel" or "channel assignment" table.

Step 1: Choose a DMX mode

Many fixtures support multiple DMX modes using different numbers of channels. The Varytec Hero Spot 90, for example, offers a 6-channel and a 16-channel mode.

Fewer channels = simpler control, less flexibility
More channels = access to fine-tuning and additional effects (e.g. 16-bit pan/tilt, individual gobo rotation, focus, prism)

You set the mode on the fixture itself - on the Hero Spot 90 this is done via Menu → DMX Channel → DMX 6 Ch / DMX 16 Ch.

The number of channels the fixture uses determines how you add it in SDC - see the section Add Fixture.

Step 2: Read the channel table

Once you've chosen a mode, find the matching channel table in the manual. Here's the Hero Spot 90 in 16-channel mode as an example:

Ch 1 - Pan
Ch 2 - Pan fine (16-bit)
Ch 3 - Tilt
Ch 4 - Tilt fine (16-bit)
Ch 5 - Pan/Tilt speed
Ch 6 - Dimmer
Ch 7 - Shutter / Strobe
Ch 8 - Color wheel
Ch 9 - Static gobo wheel
Ch 10 - Rotating gobo wheel
Ch 11 - Gobo rotation
Ch 12 - Focus
Ch 13 - Prism
Ch 14 - Auto programs
Ch 15 - Pan/Tilt auto programs
Ch 16 - Reset

In 6-channel mode, only the essential functions are available: pan (ch. 1), tilt (ch. 2), dimmer (ch. 3), strobe (ch. 4), and two auto-program channels (ch. 5–6).

When adding the fixture in SDC using an SDC fixture file, these channel numbers map directly to the channel slots you configure - see the section Add Fixture - With SDC-file. If a GDTF file is available for your fixture, SDC can set up the channel mapping automatically - see the section Add Fixture - With GDTF-file.

Step 3: Note the value ranges

Each channel uses values 0–255, and the fixture manual tells you what each value range does. This matters when using Fixture Faders or is setting a single DMX value to test your fixture.

For example, on the Hero Spot 90 shutter/strobe channel (ch. 7 in 16-channel mode):

0–4: Closed (blackout)
5–250: Strobe, increasing speed
251–255: Open (full on)

So to have the light on continuously, you need to send a value of 251 or higher on the strobe channel. Pan and tilt both use 128 as the center position, with 0 and 255 at the extremes of the movement range.

Step 4: Set the DMX start address on the fixture

The start address tells the fixture which DMX channel number corresponds to its channel 1. On the Hero Spot 90 this is set via Menu → DMX Address (values 001–512).

If you set the address to 001, channel 1 of the fixture is DMX channel 1, channel 2 is DMX channel 2, and so on. If you set it to 020, the fixture's channel 1 is DMX channel 20, channel 2 is DMX channel 21, etc.

The start address you set on the fixture must match the address you configure in SDC when adding the fixture. You can verify what SDC is actually outputting on each channel using Views → Universe Levels.