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Tiberiu Leia: Real-Time Systems Specification of RTAs 1
2. Specification
of
RT Applications
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Tiberiu Leia: Real-Time Systems Specification of RTAs 2
Contents
2.1. Construction of RT applications
2.2. Approaches of RT applications
2.3. Specification and verification with Petri nets
2.4. Transformation of Petri Nets into State Machines
and reverse
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Tiberiu Leia: Real-Time Systems Specification of RTAs 3
2.1. Construction of RT applications
Real-Time (RT) Systems involve:
RT applications RT operating systems or RT executives RT
programming languages RT hardware o microcontrollers o
microcomputers + I/O interfaces o computers + I/O interfaces o
FPGAs o PLCs etc.
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Tiberiu Leia: Real-Time Systems Specification of RTAs 4
Construction of RT Applications
RT Applications involve: hardware o computer (RT or Non RT?) o
I/O channels o controlled plant (sensors, detectors, transducers,
effectors, actuators, +?)
software o operating system (RT or Non RT, executives) o
execution environment o application program
control algorithms
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Software Waterfall model: 1. Requirements specification
2. Design
3. Implementation
4. Verification
5. Integration
6. Testing (or validation)
7. Deployment
8. Maintenance
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Control algorithm synthesis
Control engineers Control algorithms:
discrete time system
discrete event systems
hybrid systems What have to be specified?
control algorithms
plant
relation controller - plant
relation of users with plants and controllers What have to be
verified?
all the previous
software design and implementation
relations hardware - software - environment
Computer
Plant
Fig. 1. Structure of a control
application.
User
User Disturban-
ces
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Specification models Design models (diagrams) Implementation
models and programs Verification models Testing models + test
programs Deployments models Maintenance models
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2.2. Approaches of RT applications The design is based on
different types of models.
Specification it mentions what should be modeled
Overall system description
function- what its supposed to do temporal behavior - when it
does performance - how well it must do it the structure of the
system - the components of the system interfaces - how it fits in
with the environment constraints - dos and donts development - how
must it be built
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A tool for specifying real-time system should guarantee both
correctness and
completeness of the formal specification, as well as the
satisfaction of the
system behavior with respect to both the timing constraints and
the high-
level behavior descriptions.
The results: specifications
Approaches of R-T applications:
Synchronous approach activities with no durations (can be
ignored) Asynchronous approach activities have significant
durations Mixed approach activities with and without significant
durations
The differences involve:
design
scheduling
verification
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