Lamp Control — Managing Discharge Lamp Strike & Douse
DMXDesktop supports dedicated Lamp Control for managing discharge lamp Strike (turn on) and Douse (turn off) commands on beam fixtures with gas-discharge lamps (7R, 10R, 15R, etc.). This is channel type 139 ("Lamp").
Discharge lamps (Clay Paky Sharpy, Robe Pointe, Martin MAC Viper, etc.) are fundamentally different from LED fixtures. They contain a gas-filled arc tube that must be explicitly "struck" to ignite and "doused" to turn off. This is independent of the dimmer — the dimmer on discharge fixtures is typically a mechanical shutter, while the lamp itself stays lit even at 0% intensity. Operators need to strike/douse lamps at specific times during events (e.g., strike 10 minutes before the show, douse during breaks) to preserve bulb life — discharge lamps have finite lifespans of 750–2000 hours.
What Are Discharge Lamps?
Discharge lamps use a gas-filled arc tube to produce light — fundamentally different from LEDs. They must be explicitly struck (ignited) and doused (extinguished) via dedicated DMX commands.
Common fixtures with discharge lamps include:
- Clay Paky Sharpy (7R beam) — dedicated Lamp Control channel
- Robe Robin Pointe — shared "Power/Special Functions" channel with Lamp On at DMX 130–139 and Lamp Off at DMX 230–239
- Martin MAC Viper Profile
- Elation Platinum Beam 5R
- Chauvet Intimidator Beam 355 IRC
- Any moving head or spot fixture with a discharge (non-LED) lamp source
Do I need this for LED fixtures? No — LED fixtures don't have discharge lamps and don't need Strike/Douse commands.
Setting Up Lamp Control
Lamp channels can be set up in two ways:
- GDTF Import: When you import a GDTF fixture profile, the LampControl attribute is automatically detected and mapped to the Lamp channel type. Hold times are extracted from the profile when available.
- Manual Setup: You can add a Lamp channel to any fixture profile via the Channel Editor. Select channel type "Lamp" and configure the option steps to match your fixture's DMX chart.
Option Modes
The Lamp channel supports six preset types:
| Preset | Value | Description |
|---|---|---|
| No Function | off | Default/safe state |
| Lamp On | on | Strike the lamp (ignite) |
| Lamp Off | lampoff | Douse the lamp (extinguish) |
| Lamp Strike | strike | Alternative strike command (some fixtures differentiate strike vs on) |
| Standby | standby | Low-power standby mode |
| Other | other | Manufacturer-specific functions |
Configuring Hold Times in the Channel Editor
Each Lamp option step has a configurable hold time (in seconds). This is how long the DMX value must be held on the control channel before the fixture executes the command. Most fixtures require 3–5 seconds.
When editing a Lamp channel in Step Mode:
- Each option step has a "Hold" field (in seconds) next to the Enabled/Default toggles
- The hold time defines how long DMXDesktop will hold the DMX command before releasing
- Leave empty to use the default (3 seconds)
Using Strike/Douse from the Group Layout
In the Arrangement tab → Group Layout, groups containing fixtures with Lamp channels show a yellow power button in the group header (next to the Identify button).
Clicking it shows Strike (green) and Douse (red) buttons. The command is sent to ALL lamp fixtures in the group simultaneously.
What Happens When You Click Strike/Douse
- DMXDesktop sets the control channel to the correct DMX value on all lamp fixtures in the group
- Holds that value for the configured hold time (typically 3 seconds)
- Automatically releases the channel back to normal
While a command is in progress, clicking the button shows the status with a Cancel option. Only one lamp command can run at a time — starting a new command cancels any in-progress command.
FAQ
Do I need this for LED fixtures?
No — LED fixtures don't have discharge lamps. They turn on and off with the dimmer channel. Lamp Control is only for fixtures with gas-discharge lamp sources.
What happens if I strike a hot lamp?
This depends on the fixture. Most discharge lamps have a "hot re-strike" time — after being doused, they need a cooling period (typically 5–15 minutes) before they can be struck again. Attempting to strike a hot lamp usually just results in a longer ignition time rather than damage.
Can I automate strike/douse in cues?
Not yet — Lamp Control is currently manual only, triggered from the Group Layout. Cue-based automation is planned for a future update.