I was looking for real-time modeling and found the MARTE specs. I have the impression, this is intended to design systems with higher complexity as my framework. However, could be interesting to look into.
Specs: http://www.omg.org/cgi-bin/doc?formal/2011-06-02.pdf
Tutorial: http://www.uml-sysml.org/documentation/marte-tutorial-713-ko/at_download/file