(implicit signal consumption). G. Double-click on this box: the MSC Editor displays the trace of the scenario leading to the error; the end of this trace is shown in Figure 7.23. We see that process DLC in block DLCa is in state waitUAdisc. If we look at the SDL model, under this state no input or save of signal L_DataReq are specified. Therefore, this signal has been discarded. The discarded L_DataReq signal is shown in Figure 7.23. 7.3.3.2 Correct the error After examining the error, we decide that as the connection is being released, it is better losing L_DataReq than saving it. Therefore, you will add a dummy input of signal L_DataReq in state waitUAdisc of process DLC. Exhaustive Simulation 201 MSC bug_exh3 process process process <<Block DLCa>: Block DLCa>> < Block DLCb>> dispatch dispatch env_0 dispatch_3 DLC_7 AtoB_1 BtoA_2 dispatch_4 Removed beginning (47 messages) L_ReleaseReq L_ReleaseReq V76frame V76frame ( DISC .1.)) /* Not yet consumed by */ dispatch_4 waitUAdisc (DISC : (.1.)) L_DataReq ( 1, 39) L_DataReq DLC 7 1, 39 Figure 7.23 Last steps of the error MSC trace A. Exit from the Validator (answering No to the question). B. In Windows (or Unix), make a copy of the file dlc.spr into dlc_v5.spr. C. In process DLC, page part2, insert a coma followed by L_DataReq in the input containing L_ReleaseReq previously added, as illustrated in Figure 7.24. D. Save the SDL model. waitUAdisc V76frame (V76para) L_ReleaseReq, L_DataReq V76para ! present ( UA, DM) DLCstopped(me) Figure 7.24 After adding input of signal L_DataReq 7.3.3.3 Run the exhaustive simulation A. In the Organizer, select the SDL system V76test and press the Validate button. B. In the Validator, select Commands > Include Command Script, and choose sig_defs.com. C. Press on List Signal, and check that you get the same signals as previously. D. In the Validator, select Options2 > Exhaustive: Depth and enter 30. 202 Validation of Communications Systems with SDL E. Press on Exhaustive; the Validator displays: Starting exhaustive exploration Search d