TrainController Gold and Silver - Freiwald Software

X
262
Flagman
Trigger Memory
Left
Toggle
OR
Right
Table 10: Simple Track Occupancy Detection
When a train enters the track section between the track sensors the flagman is turned on
by its trigger. When the train leaves the track section, the corresponding contact indicator
is turned on. This event is again reported to the flagman through its trigger. The option
Toggle now makes sure that the flagman is turned off.
This mechanism also works if the train enters and leaves the track section on the same
side.
14.6 Prototypical Signaling
Almost each prototypical signaling system can be modeled by applying the Triggers
and Conditions (see page 256 and section 14.3) to signals. Beside Flagman elements
(see section 14.5) signals are another type of elements, to which these features can be
applied.
Especially by applying triggers to the particular states of a signal symbol, it is possible
to let this signal symbol respond to arbitrary situations with the display of an appropriate
aspect.
The following rules apply to the triggers of signals:
• The signal may change the displayed aspect, whenever an element changes its state,
that is contained in a trigger of one of the signal aspects.
• If the triggers of two signal aspects apply at the same time, then the software may
freely select one of these aspects.
• Empty triggers always apply. However, when a non-empty trigger applies at the
same time, the software selects the signal aspect associated with a non-empty trigger.
Non-empty triggers have got priority.
• Since non valid conditions may prevent a valid trigger from becoming effective (see
page 258) and a later change of the condition does not override the concerning state
change, a signal always reflects the situation when one of the triggers fired the last
time; but it does not necessarily always reflect the current situation.