t: Depth Limit: Exception limit: Optimization: Compose Unit Stop limit: Compress Unit: Scc sink limit: Observers Errors Successes Observers Error Success limit on limit on error limit on limit on success scn_observer <all> Verify Apply Cancel Figure 7.44 The Verify Options window Number of states : 20000 Number of transitions : 47926 Maximum depth reached : 16 Maximum breadth reached : 6009 duration : 0 mn 1 S Number of exceptions : 568 Number of deadlocks : 0 Number of stop conditions : 0 We see that the Simulator has executed 47 926 SDL transitions. 7.4.1.3 Replay the exception scenario During the exhaustive simulation, as soon as the Simulator discovers a problem, it stores a scenario into a file. This scenario is the sequence of transitions that are to be executed to go from the initial state of the SDL model to the state where the problem has been discovered. Here, the Simulator has generated two scenario files: v76.x1.scn and v76.x2.scn. The letter X stands for exception. The number after X is the order in which the exception was found. To get more files, you could enter a higher value for Exception Limit in the Verify Options window. 224 Validation of Communications Systems with SDL However, it is generally simpler to fix the first error, to recompile the SDL model and start a new simulation. A. In the Simulator, press the button Start MSC. B. Select File > Scenario > Load, and open v76.x1.scn. C. Press the button Redo: All. The Simulator replays the scenario, reaches the exception, and displays: Unexpected signal v76frame in dlcb!dispatch, line 312 of v76.1 pr 11 transitions executed end of scenario execution The Editor displays the MSC trace of the exception scenario, shown in Figure 7.45. bug_exh1inst_1_dlea.dispatch inst_1_atob inst_1_dlcb.dispatch PROCESS/ PROCESS/ PROCESS/ v76test/ v76test/ v76test/ dlca/dispatch(1) datalink/atob(1) dlcb/dispatch(1) I_setparmreq v76frame( xidcmd : 0 ) v76frame( xidcmd : 0 ) I_setparmreq v76frame( xidcmd : 0 ) v76frame xidcmd : 0 ) I_setparmind Figure 7.45 MSC trace o