As described in the previous section, the event machine takes actions like
reporting or switching outputs whenever a user de fined trigger goes off . This trigger is confi gured by the user with the logical combination of situations.

A situations makes reference to a vehicle state which is in fact represented by signals and their state. Syrus’ signals are of boolean nature, meaning that they can only take one of two possible values: true or false. Signals and the logical operators AND, OR, NOT are used to create logical equations to form events’ triggers.
By using the SS TAIP message a signal’s state can be consulted, and de-
pending on the signal’s type, this command can be used also to change the signal’s state.

Note: Signals’ names always have three characters.


Some examples about the use of the event machine are presented next.

Configuring two events on the Event Machine to generate an ignition report:
The ignition ON event may be defined as:

>SED18NV4;F00+< And the Ignition OFF event: >SED19NV4;F00-< Both events’ routing actions indicate that the destination of the report is the DA 4 and that EV is the reporting message to generate. Both events use a simple trigger consisting of a one-signal-only condition, F00 which is the vehicle’s ignition signal. Configuring an event that uses two signals: For this example we will use signal S00, which is associated with a speed limit and signal J00, which is associated with a heading delta. The event will be triggered when both signals are true, meaning that the vehicle exceeded the speed limit while making a turn greater than the heading delta defined: >SED05NV0;S00J00&+<