OLA DMX Trigger

ola_trigger executes programs based on the values of DMX data. This allows a lighting console to trigger events like music samples, power point presentations etc. ola_trigger supports variable assignment, which offers a flexible way to control the behavior of the

Usage

Once olad is running, you can run ola_trigger as shown:

ola_trigger example.conf

Some useful options include:

• -l, --log-level <level> Change the logging level, valid values are 0 (minimum logging) to 4 (full logs).
• -u, --universe <universe> Specifies the universe to use.

Config File Syntax

The config file defines which commands are to be run. The config file is separated into two sections: default variable assignment and action definitions.

Slot Actions

Slot actions are specified one per line, in the following form:

[Slot Offset]    [Slot Values]   [Action]

Each part must be separated by whitespace. Slot offsets range from 0 to 511. Slot values range from 0 to 255.

As an example, the following will run `echo hello world` whenever the value of the first DMX slot changes to 0, 5 or 10.

0    0,5,10    `echo hello world`

Actions are only executed when the value changes. In the example above, if the value of slot 0 in the previous frame was 10, and a frame with slot 0 @ 10 arrived, the action will not be triggered. If a frame with slot 0 @ 5 arrives, the action will execute again.

Value Matching

Values are separated by commas. Ranges can be specified with a hyphen.

1,2,3,4   # Trigger on values 1 through to 4
1-4,10-14 # Trigger on values 1 to 4 and 10 to 14 (inclusive)

The % character the is default match. It triggers for all values that don't have an explicit action configured

0-100  # Values 0 to 100
%         # Triggers for everything else (101 - 255)

Variables

Rather than executing a command, an action can set a variable

Special Variables

The variables ${slot_offset} and ${slot_value}

Comments

The # character comments out the rest of the text until the end of the line. This can be used at any location.

Example

A full example config is provided in the tools/ola_trigger directory.

# Example DMX Trigger Config File                                                                                                                                                               

# Variable definitions
###############################################################################
# The default value of slot 2, this won't ever be used, since the variable is
# only used with slot 3, which implies we already got data for slot 2.
slot_2_value = "nan"  # nan isn't special in any way

# Triggers
###############################################################################
# Slot    Trigger Values   Action

# Slot 0 prints the current value of slot 0
0         %                `echo "Slot ${slot_offset} is at ${slot_value}"`

# Slot 1 runs a different command line tools
1         1                `ls`
1         2                `ps aux`
1         3                `who`

# Slot 2 sets a variable
2         %                slot_2_value="${slot_value}"

# Slot 3 prints the value of slot3 if slot3 is greater than 50%
3         128-255          `echo "Slot 2 is ${slot_2_value}"`