Tutorial
Page 4 Real Time Developer Studio V4.3
code on the target, channels have no direct implementation; they are only used
for structuring the software and defining the interfaces.
•Behavior
A process behavior is described graphically as a finite state machine. Internal
process states, events (messages), decisions, timer manipulations, semaphore
manipulations have specific symbols briefly summarized below necessary to
understand the following tutorial:
SDL or SDL-RT procedures can be called within the process behavior descrip-
tion. In SDL-RT, C functions can be called as well; SDL also allows the call of C
function via external operators.
• Data and syntax
This is where SDL and SDL-RT differ the most:
• In SDL, data is defined via ADT (Abstract Data Types), using specific con-
cepts and notations. The data manipulation has also a specific syntax, derived
from languages such as Pascal.
• In SDL-RT, the C language is used to define and manipulate data, making
things more familiar to developers…
Another SDL-RT specificity is the integration of UML use case and class diagrams for
less time-critical parts of the system. Objects can be associated to processes or blocks and
used in the behavioral parts of the processes.
In both SDL and SDL-RT projects, RTDS also integrates the Message Sequence Chart
dynamic view. On such a diagram, time flows from top to bottom. Lifelines represent
agents, semaphores or objects and key SDL-RT events are represented. The diagram
emphasizes the sequence in which the events occur.
Would you need any extra information on the diagrams and their meaning, the following
references may be used:
• For SDL, the SDL Forum web-site has many tutorials and presentations:
http://www.sdl-forum.org/
• For SDL-RT, the reference manual is available in RTDS via the Help / SDL-RT ref-
erence menu. This manual is also available on the SDL-RT web-site:
http://www.sdl-rt.org
Start
State
Input
Output
Plain C code
Decision
Start timer
Stop timer
Take semaphore
Give semaphore
Create task
Declarations
SDL-RT only
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