Sep 20, 2021 - SDL-RT V2.4 is now available introducing:

  • Message broadcast,
  • Re-organized change log.

Apr 23, 2013 - SDL-RT V2.3 is now available introducing:

  • New MSC XML format,
  • Property Sequence Chart introduction.

Oct 16, 2012 - ITU-T Appendix C of the Z.104 to support C language in SDL standard.

Jan 25, 2010 - ITU-T SDL roadmap for 2010 is to open the standard to other data types paving the way to SDL-RT standardization.

Sep 1, 2006 - SDL-RT V2.2 is now available introducing:

  • advanced object oriented features,
  • composite states.

Mar 17, 2004 - Last web statistics show the SDL-RT pdf document is downloaded 400 times a month in average.

Oct 1, 2003 - SDL-RT V2.1 is now available introducing multiple parameters in messages.

SDL-RT standard now available in Chinese.

Mar 25, 2003 - SDL-RT V2.0 introduced:

  • UML class diagram,
  • UML deployment diagram,
  • STACK size definition.

should read this
SDL-RT has been designed for the real time developer teams looking for graphical representations of traditional concepts used in their domain without leaving behind legacy code and years of experience.

It brings abstraction with graphical representations to define:

  • architecture (tasks gathered in functional blocks)
  • communication (message exhanges and semaphores)
  • behavior (message input and output, semaphores and timers manipulations, internal states modifications)

At the same time it keeps precision of traditionnal techniques because C language is embedded in SDL-RT.

Last but not least, SDL-RT is object oriented where it needs to be. UML class diagram is part of SDL-RT and specific graphical representations have been defined to represent active classes (tasks) and passive classes (C++ objects). Active classes represent functional blocks or tasks and specialization allows to graphically and easily re-use a real time software component.

SDL-RT has been designed by real time developers for real time developers. If you want to comment or suggest improvements please do not hesitate to send us a mail.

to do with it
SDL-RT prime use is to develop real time and embedded software. SDL-RT is based on tasks running concurrently that exchange information through messages and synchronize with each other using semaphores. Any development team willing to base their development on a Real Time Operating System (RTOS) should have a look at SDL-RT.

SDL-RT has been designed so that tools supporting it can provide:

  • grapical debuging such as breakpoints and stepping in SDL-RT diagrams and
  • graphical tracing with the Message Sequence Chart.

SDL-RT concepts are so close to RTOS concepts that integration with any RTOS, RTOS simulator, or target debuger is straightforward.

These concepts are used in a variety of domains such as:

  • Telecommunication
  • Car industry
  • Automation
  • Aeronautics
  • Medical
  • Defense

can I find it
A good standard should meet three obvious basic conditions:
  • Free
  • Legible
  • Useful

SDL-RT standard is right here for free in html or pdf format. It does not use any weird notations and is full of examples.

Embedding C language in SDL has been implemented in very large companies in an informal way. SDL-RT is just formalizing techniques that have been proven useful for years.

SDL-RT respects techniques that have been used for decades. In that sense it is an evolution in real time programming not a revolution that would throw everything away.

html on-line standard

pdf standard

pdf Chinese standard

DTD download