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Chapter 10. openETCS Model
be explained in the following Subsection 10.4.2. A balise telegram always terminates with an
“End of Information” packet [85, p. 30].
10.4.2. Balise Content
All available ETCS packets are modelled in a gAnyPacket graph. According to the initial
description of the gAnyPacket graph type in Subsection 7.3.8, the model in Figure 10.29 only
holds a set of oPacket objects without any bindings. The models or rather decompositions of
some exemplary packets will be discussed in the following subsections.
Level 1 Movement
Authority
Gradient Profile
National Values
International Static
Speed Profile
Stop if in Staff
Responsible
Repositioning
Information
Level Transition
Order
Linking
Figure 10.29.: Available packets as gAnyPacket graph
10.4.3. Level Transition Order Packet
The “Level Transition Order” packet [85, p. 14] is used to order a train to switch to a
new Application Level. This was described for the Unfitted Mode in Subsection 10.2.3.
The three very first oVariableInstance objects define only general information of the packet.
“NID_PACKET” [85, p. 47] is the unique numerical ID of each packet, “Q_DIR” [85, p. 49]
defines, which movement directions of the train the packet is valid for, and “L_PACKET” [85,
p. 37] is the size of the telegram in bits.
“Q_SCALE” [85, p. 54] is a scaling qualifier, which is applied by the “Scaling” relationship
(see Subsection 7.3.7) to all distances and lengths in this packet. “D_LEVELTR” [85, p. 32]
holds the distance to the level transition itself. On the one hand, “M_LEVELTR” [85, p. 41]
holds the information about the new Application Level to be switched to. On the other hand,
it is also a conditional iterator for the oVariableInstance object “NID_STM” [85, p. 37], which
holds the identifier to the required STM. Nevertheless, because this case study only includes
Application Level 0 and 1, this oVariableInstance object is never used and is only modelled for
completeness.
“L_ACKLEVELTR” [85, p. 36] represents the length of the area, in which the driver has to
acknowledge the level transition via the DMI.
The oVariableInstance object “N_ITER” [85, p. 4] gives the possibility to define multiple Level
transitions in one packet by iterating over oVariableInstance objects of the same oVariableType
objects (“M_LEVELTR_T”, “NID_STM_T”, and “L_ACKLEVELTR_T”) that were used
before.
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