PragmaDev MSC tracer is a graphical tracing tool based on ITU-T Message Sequence Chart and on OMG UML2.0 Sequence Diagram standards. It allows to trace on-line or off-line your target behavior with a standard graphical representation.
The MSC Tracer can run with an Real Time Developer Studio license or a cheap dedicated MSC Tracer license. A free MSC Tracer version is also available that runs without any license in which the diagrams can not be saved.