Observables are data that is constantly monitored. When the data matches a criteria, a list of actions or commands is executed.

For people familiar with the concept, it can be considered a if-this-then-that instruction. For example: If the weather data from the simulator indicates rain is falling on the aircraft, we can set the windshield wipers automatically.

Observables are defined at the aircraft level.

Definition

The file observables.yaml is located in the deckconfig/resources folder of an aircraft. It is loaded on startup.

observables:
  - name: example
    trigger: onchange
    dataref: some/dataref/to/check
    actions:
      - command: do/some/action
        delay: 5

Attribute

Observables

The observables attribute is a list of individual observables.

Observable

Attributes

Trigger

True/False Evaluation

The trigger attribute of an observable is a single dataref or a formula that is evaluated each time a dataref mentioned in the formula changes. The result of a the formula is compared to 0, i.e. True (different from zero) or False (equal to zero).

If the result of the formula is True, commands listed into the actions attributes are executed.

Value Changed

Another method to trigger the flow of action(s) is to select the value changed mode. Actions get executed as the value of the dataref or of the computation has changed.

Observable

The observable is the data that is monitored. It can either be a single dataref or a formula.

Actions

The actions attribute is a list of individual actions that gets carried out in sequence if the trigger attribute is True.

Action

Attributes

An action as the same attribute as a command carried out by a button:

• instruction
• delay
• condition