Architecture Modeling - SPES 2020

Architecture Modeling
Figure 5.20: Unit Level – Allocation from Logical to Technical Perspective
ECU1 has two contracts specifying the local deadlines for the execution of the two tasks
ECU1Task1 and ECU1Task2. To choose the correct deadlines here, the allocation of logical
components to tasks of the technical perspective is necessary. The allocation is depicted in
Figure 5.20 while we use here an abbreviatory representation of the mapping of a single port
to another single port. A dotted arrow from a port a of a logical component (depicted on the
left side) to a port b of a technical component (depicted on the right side) means a mapping of
port a to port b. The dottet arrow from one component to another component annotated with an
> label indicates this mapping as an allocation.
For ECU1, the relevant allocation decisions are the mapping of Monitor1 to ECU1Task2
and the mapping of Command2 to ECU1Task1. This leads to the contracts in Figure 5.19
specifying the same deadlines as for the mapped logical components i.e. a deadline of 1200
microseconds for the execution (inclusive scheduling) of ECU1Task2 (delay from input signal
inA.P TecBusA to outA.P TecA) and a deadline of 1400 microseconds for ECU1Task1
(delay from input signal inB.P TecB to outB.P TecBusB).
The structure of the component ECU2 is almost similar to ECU1 and thus not depicted here.
The mapping to the tasks of ECU2 is also shown in the allocation in Figure 5.20. Communication
components such as Com1ToMon1 and Com2ToMon2 are mapped implicitly by the task
mapping.
The interna of the bus component CANBus are shown in Figure 5.21. It consists of a scheduler
component (depicted in blue) that schedules two slots (depicted in green). Each slot is then
linked to a frame-triggering component that sends and receives the frames. Again, we have two
contracts specifying how long a communication may take which is the identical deadline of 400
microseconds as for the logical communication components.
Scheduling Analysis with Orca Next, we want to show exemplarily how real-time contracts
may be checked using a scheduling analysis tool like Orca.
The first step is the translation of the model into the Orca data model. The result of this
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