The Lighting Command Language

QLab 4 introduces a textual light command language which you can use to control your lighting instruments. At its core, every light cue contains a plain block of text which is interpreted as this command language. The basic formats of a command are as follows:

instrument = value
instrument.parameter = value
group = value
group.parameter = value

Note that spaces in a lighting command are always optional.

When a command omits a parameter, QLab fills in the default parameter as specified by the instrument's definition. Typically, this default parameter is intensity but it can be any parameter.

When a command refers to group.parameter, the value is passed to all instruments within the group that have that parameter. So the command would set the blue parameter of any instruments in that group to 50. Instruments which do not have the given parameter are ignored.


An instrument or group can be set to the reserved value pass to explicitly prevent them from being adjusted by the current cue. Consider a show with a group called backlight, and three instruments in the group called left, center, and right. If a cue consists of the following commands:

backlight = 75
center = pass

the results would be left and right set to 75, and center left un-adjusted.


The command instrument = home or instrument.parameter = home sets the instrument or parameter to its home value, as specified in the instrument definition. For example, the included "dimmer" definition has a home value of 0, so setting an instrument that uses the dimmer definition to home turns it off. The included "DMX iris" definition has a home value of 100, so setting an instrument that uses the DMX iris definition to home opens the iris all the way.


A lighting command can also refer to a range of instruments:

1 - 3 = 50
10, 12, 14 = 75

The range will be expanded to its constituent commands before being added to the cue, or applied to the Dashboard. Thus, the commands above would appear in a cue as:

1 = 50
2 = 50
3 = 50
10 = 75
12 = 75
14 = 75

Ad-hoc Groups

You can alternately define an "ad-hoc" group by enclosing a range in brackets:

[1 - 3] = 50
[10, 12, 14] = 50

Bracketed commands remain as single commands in the cue, and behave just like groups.

Up arrow

The up arrow key scrolls through the history of the command line, providing an easy way to experiment with a level. For example:

1 = 80 |Enter|
70 |Enter|
75 |Enter|

Instrument 1 is set to 80, then 70, then 75, and reentering the 1= is not necessary.