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11.3. Simulation Model
The states of the EVC simulation are introduced below:
No_Power
Stand_By
Moving_in_Unfitted
Moving_in_Staff_Responsible
Stopping_in_Trip
Stopped_in_Post_Trip
Isolated
According to the ETCS SRS and the corresponding open-
ETCS model in Subsection 10.2.1, this state only checks if
the emergency brakes are activated and if the “ETCS Mode”
DMI output field holds the string “No Power”. Since no
movement can be simulated in this state, transitions to other
states can only be done by signals (in Figure 11.6) from
the CDMI state machine. For example, the powering of the
system / EVC, which is indicated by the bSystemPowered
variable.
This state does not differ much from the (normally) preceding
“No_Power” state because again it is checked if the
emergency brake is activated and the “ETCS Mode” DMI
output field holds the name of the current Mode. Also,
the corresponding manipulation of the DMI is done by
the CDMI machine from Subsection 11.3.2 by entering the
static train data.
The train movement starts in the ETCS Mode Unfitted if
the Application Level is 0, which is the default case in the
simulation. Since various ATP functionalities are tested in
this state, which are modelled in a sub-state machine, this
state only has an assertion for the correct “ETCS Mode”
DMI output field as entry-action [64]. Further assertions
are defined in its decomposition.
In this state, similar to “Moving_in_Unfitted”, only the
correct value of the “ETCS Mode” DMI is checked. The concrete
functionality and the corresponding correct behaviour
is tested in a sub-state machine.
According to the model in Subsection 10.2.6, the emergency
brake must be activated in this Mode and the correct ETCS
Mode string must be displayed in the DMI.
This state can only be executed directly after “Stopping_-
in_Trip”. In contrast to the preceding state, the emergency
brake must not be used here, which is explicitly tested by
an assert statement. Again, the ATP functionality is tested
in a sub-state machine.
Since ETCS does not provide any ATP functionality in
Mode Isolated, only the correct value of the “ETCS Mode”
DMI output field is tested. Furthermore, the simulation
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